diff --git a/SPECS.md b/SPECS.md
index 410abca..85c5a6f 100644
--- a/SPECS.md
+++ b/SPECS.md
@@ -112,8 +112,11 @@ tyre pressures, GPS (lat, lon, elevation, heading) and the is_* flags. It does *
   INGEST_TOKEN) into git and pushed it. Commit amended and force-pushed; both values regenerated in
   the now gitignored `k8s/secrets.yaml` (since moved to `k8s/secrets/secrets.yaml`, outside
   `kubectl apply -f k8s/`). Filled-in secrets live only there from now on.
+- 2026-10-18 — App 2.16.4: drop-downs again, as Material exposed dropdown menus: their list leaves
+  the focus with the activity, so full screen stays (a Spinner's list is a focusable window of its
+  own without the full-screen flags). 2.16.3 had replaced them with buttons.
 - 2026-10-18 — App 2.16.3: full screen stays while choosing or reading a dialog. Drop-downs (upload
-  frequency, tyre unit, accent colour) are now buttons on the page: a drop-down is a window of its
+  frequency, tyre unit, accent colour) became buttons on the page: a drop-down is a window of its
   own without the full-screen flags, so the car showed its bars while it was open. Dialogs are
   shown unfocusable, given the activity's full-screen flags, then allowed focus
   (`showKeepingFullScreen`); none of them takes typing.
diff --git a/app/build.gradle b/app/build.gradle
index baed5bc..cb04d10 100644
--- a/app/build.gradle
+++ b/app/build.gradle
@@ -34,8 +34,8 @@ android {
         applicationId "com.stinnesbeck.nilsmg4"
         minSdk 27
         targetSdk 36
-        versionCode 87
-        versionName "2.16.3"
+        versionCode 88
+        versionName "2.16.4"
 
         // Nothing about the server ships in the APK: its URL and ingest token are entered in
         // the app's Server tab (ServerConfig), and the database is only reachable by the server.
diff --git a/app/src/main/java/com/evsuite/abrp/MainActivity.java b/app/src/main/java/com/evsuite/abrp/MainActivity.java
index eb48a7b..3ddcdf4 100644
--- a/app/src/main/java/com/evsuite/abrp/MainActivity.java
+++ b/app/src/main/java/com/evsuite/abrp/MainActivity.java
@@ -126,7 +126,7 @@ public class MainActivity extends AppCompatActivity {
     /** Upload page: live telemetry switch and cadence. */
     private SwitchMaterial liveTelemetrySwitch, boostSwitch, voiceKeySwitch, fullScreenSwitch;
     private TextView steeringKeysText;
-    private com.google.android.material.chip.ChipGroup intervalChoices;
+    private com.google.android.material.textfield.MaterialAutoCompleteTextView intervalChoices;
     private TextInputLayout lowSocLayout;
     private TextInputEditText lowSocInput;
 
@@ -1126,28 +1126,18 @@ public class MainActivity extends AppCompatActivity {
     }
 
     /**
-     * A single choice as buttons on the page (choice_chip.xml), in place of a drop-down: a
-     * drop-down opens a window of its own that is not full screen, and the car's bars came back
-     * while it was open. Rebinding replaces the buttons, so it may be called again.
+     * A single choice as a drop-down (Widget.EV.Dropdown). An exposed dropdown menu rather than
+     * a Spinner: a Spinner's list is a focusable window of its own without the full-screen
+     * flags, and the car showed its bars while it was open; this list leaves the focus with
+     * the activity. setSimpleItems keeps every option listed (a plain adapter would filter the
+     * list down to the current text). Rebinding is safe.
      */
-    private void bindChoices(com.google.android.material.chip.ChipGroup group, String[] labels, int selected,
-                             java.util.function.IntConsumer onPick) {
-        group.setOnCheckedStateChangeListener(null);
-        group.removeAllViews();
-        for (int i = 0; i < labels.length; i++) {
-            com.google.android.material.chip.Chip chip = (com.google.android.material.chip.Chip)
-                    getLayoutInflater().inflate(R.layout.choice_chip, group, false);
-            chip.setId(View.generateViewId());
-            chip.setText(labels[i]);
-            chip.setTag(i);
-            group.addView(chip);
-            if (i == selected) chip.setChecked(true);
-        }
-        group.setOnCheckedStateChangeListener((g, checkedIds) -> {
-            if (checkedIds.isEmpty()) return;
-            View chosen = g.findViewById(checkedIds.get(0));
-            if (chosen != null) onPick.accept((Integer) chosen.getTag());
-        });
+    private void bindChoices(com.google.android.material.textfield.MaterialAutoCompleteTextView view,
+                             String[] labels, int selected, java.util.function.IntConsumer onPick) {
+        view.setOnItemClickListener(null);
+        view.setSimpleItems(labels);
+        view.setText(labels[selected], false);
+        view.setOnItemClickListener((parent, item, position, id) -> onPick.accept(position));
     }
 
     /** The accent colour; a change recreates the activity so every view takes it. */
diff --git a/app/src/main/res/color/choice_background.xml b/app/src/main/res/color/choice_background.xml
deleted file mode 100644
index c941703..0000000
--- a/app/src/main/res/color/choice_background.xml
+++ /dev/null
@@ -1,5 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<selector xmlns:android="http://schemas.android.com/apk/res/android">
-    <item android:state_checked="true" android:color="?attr/evAccentSurface" />
-    <item android:color="@color/ev_surface_raised" />
-</selector>
diff --git a/app/src/main/res/color/choice_stroke.xml b/app/src/main/res/color/choice_stroke.xml
deleted file mode 100644
index c0e21ef..0000000
--- a/app/src/main/res/color/choice_stroke.xml
+++ /dev/null
@@ -1,5 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<selector xmlns:android="http://schemas.android.com/apk/res/android">
-    <item android:state_checked="true" android:color="?attr/evAccent" />
-    <item android:color="@color/ev_outline" />
-</selector>
diff --git a/app/src/main/res/color/choice_text.xml b/app/src/main/res/color/choice_text.xml
deleted file mode 100644
index 60b46ae..0000000
--- a/app/src/main/res/color/choice_text.xml
+++ /dev/null
@@ -1,5 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<selector xmlns:android="http://schemas.android.com/apk/res/android">
-    <item android:state_checked="true" android:color="?attr/evAccent" />
-    <item android:color="@color/ev_text_primary" />
-</selector>
diff --git a/app/src/main/res/layout-w1000dp/pane_service.xml b/app/src/main/res/layout-w1000dp/pane_service.xml
index bdff841..1298c51 100644
--- a/app/src/main/res/layout-w1000dp/pane_service.xml
+++ b/app/src/main/res/layout-w1000dp/pane_service.xml
@@ -27,7 +27,9 @@
             <LinearLayout android:layout_width="match_parent" android:layout_height="wrap_content" android:orientation="vertical" android:padding="24dp" android:background="@drawable/bg_glass">
                 <TextView android:layout_width="match_parent" android:layout_height="wrap_content" android:text="@string/design_service_timing" android:textAppearance="@style/Text.EV.Eyebrow" />
                 <TextView android:layout_width="match_parent" android:layout_height="wrap_content" android:text="@string/label_frequency" android:textAppearance="@style/Text.EV.Body" android:layout_marginTop="20dp" />
-                <com.google.android.material.chip.ChipGroup android:id="@+id/interval_choices" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_marginTop="12dp" app:singleSelection="true" app:selectionRequired="true" app:chipSpacingHorizontal="12dp" app:chipSpacingVertical="8dp" />
+                <com.google.android.material.textfield.TextInputLayout style="@style/Widget.EV.Dropdown" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_marginTop="12dp">
+                    <com.google.android.material.textfield.MaterialAutoCompleteTextView android:id="@+id/interval_choices" android:layout_width="match_parent" android:layout_height="wrap_content" android:minHeight="72dp" android:inputType="none" android:textSize="20sp" app:simpleItemLayout="@layout/dropdown_item" />
+                </com.google.android.material.textfield.TextInputLayout>
                 <TextView android:layout_width="match_parent" android:layout_height="wrap_content" android:text="@string/hint_frequency" android:textAppearance="@style/Text.EV.Secondary" android:layout_marginTop="12dp" />
                 <com.google.android.material.switchmaterial.SwitchMaterial android:id="@+id/boost_switch" android:layout_width="match_parent" android:layout_height="wrap_content" android:minHeight="72dp" android:text="@string/label_boost_low_soc" android:textAppearance="@style/Text.EV.Body" android:paddingTop="8dp" android:paddingBottom="8dp" app:useMaterialThemeColors="true" app:thumbTint="@color/switch_thumb" app:trackTint="@color/switch_track" android:textColor="@color/ev_text_primary" />
                 <com.google.android.material.textfield.TextInputLayout android:id="@+id/low_soc_layout" style="@style/Widget.EV.Input" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_marginTop="12dp" android:hint="@string/label_low_soc_threshold">
diff --git a/app/src/main/res/layout-w1000dp/pane_settings.xml b/app/src/main/res/layout-w1000dp/pane_settings.xml
index a096c71..113c246 100644
--- a/app/src/main/res/layout-w1000dp/pane_settings.xml
+++ b/app/src/main/res/layout-w1000dp/pane_settings.xml
@@ -9,9 +9,13 @@
                 <com.google.android.material.switchmaterial.SwitchMaterial android:id="@+id/voice_key_switch" android:layout_width="match_parent" android:layout_height="wrap_content" android:minHeight="72dp" android:text="@string/label_voice_key" android:textAppearance="@style/Text.EV.Body" android:paddingTop="8dp" android:paddingBottom="8dp" app:useMaterialThemeColors="true" app:thumbTint="@color/switch_thumb" app:trackTint="@color/switch_track" android:textColor="@color/ev_text_primary" />
                 <TextView android:layout_width="match_parent" android:layout_height="wrap_content" android:text="@string/hint_voice_key" android:textAppearance="@style/Text.EV.Secondary" />
                 <TextView android:layout_width="match_parent" android:layout_height="wrap_content" android:text="@string/label_tire_unit" android:textAppearance="@style/Text.EV.Body" android:layout_marginTop="20dp" />
-                <com.google.android.material.chip.ChipGroup android:id="@+id/tire_unit_choices" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_marginTop="12dp" app:singleSelection="true" app:selectionRequired="true" app:chipSpacingHorizontal="12dp" app:chipSpacingVertical="8dp" />
+                <com.google.android.material.textfield.TextInputLayout style="@style/Widget.EV.Dropdown" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_marginTop="12dp">
+                    <com.google.android.material.textfield.MaterialAutoCompleteTextView android:id="@+id/tire_unit_choices" android:layout_width="match_parent" android:layout_height="wrap_content" android:minHeight="72dp" android:inputType="none" android:textSize="20sp" app:simpleItemLayout="@layout/dropdown_item" />
+                </com.google.android.material.textfield.TextInputLayout>
                 <TextView android:layout_width="match_parent" android:layout_height="wrap_content" android:text="@string/label_accent" android:textAppearance="@style/Text.EV.Body" android:layout_marginTop="20dp" />
-                <com.google.android.material.chip.ChipGroup android:id="@+id/accent_choices" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_marginTop="12dp" app:singleSelection="true" app:selectionRequired="true" app:chipSpacingHorizontal="12dp" app:chipSpacingVertical="8dp" />
+                <com.google.android.material.textfield.TextInputLayout style="@style/Widget.EV.Dropdown" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_marginTop="12dp">
+                    <com.google.android.material.textfield.MaterialAutoCompleteTextView android:id="@+id/accent_choices" android:layout_width="match_parent" android:layout_height="wrap_content" android:minHeight="72dp" android:inputType="none" android:textSize="20sp" app:simpleItemLayout="@layout/dropdown_item" />
+                </com.google.android.material.textfield.TextInputLayout>
             </LinearLayout>
             <LinearLayout android:layout_width="match_parent" android:layout_height="wrap_content" android:orientation="vertical" android:padding="24dp" android:background="@drawable/bg_glass" android:layout_marginTop="16dp">
                 <TextView android:layout_width="match_parent" android:layout_height="wrap_content" android:text="@string/design_battery_settings_title" android:textAppearance="@style/Text.EV.Eyebrow" />
diff --git a/app/src/main/res/layout/choice_chip.xml b/app/src/main/res/layout/choice_chip.xml
deleted file mode 100644
index f0f8440..0000000
--- a/app/src/main/res/layout/choice_chip.xml
+++ /dev/null
@@ -1,8 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<!-- One option of an on-page choice (MainActivity.bindChoices). Chips rather than a drop-down:
-     a drop-down opens its own window, which is not full screen, so the car's bars came back
-     while it was open; and one tap is easier than two while driving. -->
-<com.google.android.material.chip.Chip xmlns:android="http://schemas.android.com/apk/res/android"
-    style="@style/Widget.EV.Choice"
-    android:layout_width="wrap_content"
-    android:layout_height="wrap_content" />
diff --git a/app/src/main/res/layout/dropdown_item.xml b/app/src/main/res/layout/dropdown_item.xml
new file mode 100644
index 0000000..623a16f
--- /dev/null
+++ b/app/src/main/res/layout/dropdown_item.xml
@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- One row of a drop-down list (Widget.EV.Dropdown): a full touch target, body text size. -->
+<TextView xmlns:android="http://schemas.android.com/apk/res/android"
+    android:layout_width="match_parent"
+    android:layout_height="wrap_content"
+    android:minHeight="@dimen/touch_target"
+    android:gravity="center_vertical"
+    android:paddingStart="20dp"
+    android:paddingEnd="20dp"
+    android:textAppearance="@style/Text.EV.Body"
+    android:textColor="@color/ev_text_primary"
+    android:maxLines="1"
+    android:ellipsize="end" />
diff --git a/app/src/main/res/layout/pane_service.xml b/app/src/main/res/layout/pane_service.xml
index d29a516..b53b64f 100644
--- a/app/src/main/res/layout/pane_service.xml
+++ b/app/src/main/res/layout/pane_service.xml
@@ -24,7 +24,9 @@
         <LinearLayout android:layout_width="match_parent" android:layout_height="wrap_content" android:orientation="vertical" android:padding="24dp" android:background="@drawable/bg_glass" android:layout_marginTop="16dp">
             <TextView android:layout_width="match_parent" android:layout_height="wrap_content" android:text="@string/design_service_timing" android:textAppearance="@style/Text.EV.Eyebrow" />
             <TextView android:layout_width="match_parent" android:layout_height="wrap_content" android:text="@string/label_frequency" android:textAppearance="@style/Text.EV.Body" android:layout_marginTop="20dp" />
-            <com.google.android.material.chip.ChipGroup android:id="@+id/interval_choices" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_marginTop="12dp" app:singleSelection="true" app:selectionRequired="true" app:chipSpacingHorizontal="12dp" app:chipSpacingVertical="8dp" />
+            <com.google.android.material.textfield.TextInputLayout style="@style/Widget.EV.Dropdown" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_marginTop="12dp">
+                <com.google.android.material.textfield.MaterialAutoCompleteTextView android:id="@+id/interval_choices" android:layout_width="match_parent" android:layout_height="wrap_content" android:minHeight="72dp" android:inputType="none" android:textSize="20sp" app:simpleItemLayout="@layout/dropdown_item" />
+            </com.google.android.material.textfield.TextInputLayout>
             <TextView android:layout_width="match_parent" android:layout_height="wrap_content" android:text="@string/hint_frequency" android:textAppearance="@style/Text.EV.Secondary" android:layout_marginTop="12dp" />
             <com.google.android.material.switchmaterial.SwitchMaterial android:id="@+id/boost_switch" android:layout_width="match_parent" android:layout_height="wrap_content" android:minHeight="72dp" android:text="@string/label_boost_low_soc" android:textAppearance="@style/Text.EV.Body" android:paddingTop="8dp" android:paddingBottom="8dp" app:useMaterialThemeColors="true" app:thumbTint="@color/switch_thumb" app:trackTint="@color/switch_track" android:textColor="@color/ev_text_primary" />
             <com.google.android.material.textfield.TextInputLayout android:id="@+id/low_soc_layout" style="@style/Widget.EV.Input" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_marginTop="12dp" android:hint="@string/label_low_soc_threshold">
diff --git a/app/src/main/res/layout/pane_settings.xml b/app/src/main/res/layout/pane_settings.xml
index 0a5b350..ced79f4 100644
--- a/app/src/main/res/layout/pane_settings.xml
+++ b/app/src/main/res/layout/pane_settings.xml
@@ -8,9 +8,13 @@
             <com.google.android.material.switchmaterial.SwitchMaterial android:id="@+id/voice_key_switch" android:layout_width="match_parent" android:layout_height="wrap_content" android:minHeight="72dp" android:text="@string/label_voice_key" android:textAppearance="@style/Text.EV.Body" android:paddingTop="8dp" android:paddingBottom="8dp" app:useMaterialThemeColors="true" app:thumbTint="@color/switch_thumb" app:trackTint="@color/switch_track" android:textColor="@color/ev_text_primary" />
             <TextView android:layout_width="match_parent" android:layout_height="wrap_content" android:text="@string/hint_voice_key" android:textAppearance="@style/Text.EV.Secondary" />
             <TextView android:layout_width="match_parent" android:layout_height="wrap_content" android:text="@string/label_tire_unit" android:textAppearance="@style/Text.EV.Body" android:layout_marginTop="20dp" />
-            <com.google.android.material.chip.ChipGroup android:id="@+id/tire_unit_choices" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_marginTop="12dp" app:singleSelection="true" app:selectionRequired="true" app:chipSpacingHorizontal="12dp" app:chipSpacingVertical="8dp" />
+            <com.google.android.material.textfield.TextInputLayout style="@style/Widget.EV.Dropdown" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_marginTop="12dp">
+                <com.google.android.material.textfield.MaterialAutoCompleteTextView android:id="@+id/tire_unit_choices" android:layout_width="match_parent" android:layout_height="wrap_content" android:minHeight="72dp" android:inputType="none" android:textSize="20sp" app:simpleItemLayout="@layout/dropdown_item" />
+            </com.google.android.material.textfield.TextInputLayout>
             <TextView android:layout_width="match_parent" android:layout_height="wrap_content" android:text="@string/label_accent" android:textAppearance="@style/Text.EV.Body" android:layout_marginTop="20dp" />
-            <com.google.android.material.chip.ChipGroup android:id="@+id/accent_choices" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_marginTop="12dp" app:singleSelection="true" app:selectionRequired="true" app:chipSpacingHorizontal="12dp" app:chipSpacingVertical="8dp" />
+            <com.google.android.material.textfield.TextInputLayout style="@style/Widget.EV.Dropdown" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_marginTop="12dp">
+                <com.google.android.material.textfield.MaterialAutoCompleteTextView android:id="@+id/accent_choices" android:layout_width="match_parent" android:layout_height="wrap_content" android:minHeight="72dp" android:inputType="none" android:textSize="20sp" app:simpleItemLayout="@layout/dropdown_item" />
+            </com.google.android.material.textfield.TextInputLayout>
         </LinearLayout>
         <LinearLayout android:layout_width="match_parent" android:layout_height="wrap_content" android:orientation="vertical" android:padding="24dp" android:background="@drawable/bg_glass" android:layout_marginTop="16dp">
             <TextView android:layout_width="match_parent" android:layout_height="wrap_content" android:text="@string/design_battery_settings_title" android:textAppearance="@style/Text.EV.Eyebrow" />
diff --git a/app/src/main/res/values/styles_app.xml b/app/src/main/res/values/styles_app.xml
index 1b39cf5..7c74ff9 100644
--- a/app/src/main/res/values/styles_app.xml
+++ b/app/src/main/res/values/styles_app.xml
@@ -43,6 +43,19 @@
     <item name="endIconTint">@color/ev_text_secondary</item>
     <item name="helperTextTextAppearance">@style/Text.EV.Secondary</item>
   </style>
+  <!-- A drop-down that keeps the app full screen: an exposed dropdown menu's list does not take
+       focus from the activity's window, unlike a Spinner's, so the car's bars stay hidden. -->
+  <style name="Widget.EV.Dropdown" parent="Widget.Material3.TextInputLayout.OutlinedBox.ExposedDropdownMenu">
+    <item name="boxBackgroundColor">@color/ev_background</item>
+    <item name="boxStrokeColor">@color/input_stroke</item>
+    <item name="boxStrokeWidth">1dp</item>
+    <item name="boxStrokeWidthFocused">2dp</item>
+    <item name="boxCornerRadiusTopStart">16dp</item>
+    <item name="boxCornerRadiusTopEnd">16dp</item>
+    <item name="boxCornerRadiusBottomStart">16dp</item>
+    <item name="boxCornerRadiusBottomEnd">16dp</item>
+    <item name="endIconTint">?attr/evAccent</item>
+  </style>
   <style name="Text.EV.Eyebrow" parent="Text.EV.SectionHeader">
     <item name="android:textSize">16sp</item>
     <item name="android:textColor">?attr/evAccent</item>
diff --git a/app/src/main/res/values/styles_ev.xml b/app/src/main/res/values/styles_ev.xml
index 97533f0..fcafe9a 100644
--- a/app/src/main/res/values/styles_ev.xml
+++ b/app/src/main/res/values/styles_ev.xml
@@ -97,19 +97,4 @@
         <item name="cornerSize">18dp</item>
     </style>
 
-    <!-- On-page single choice (choice_chip.xml): a full touch target, the accent when chosen. -->
-    <style name="Widget.EV.Choice" parent="Widget.Material3.Chip.Filter">
-        <item name="android:checkable">true</item>
-        <item name="checkedIconVisible">false</item>
-        <item name="chipMinHeight">@dimen/touch_target</item>
-        <item name="chipMinTouchTargetSize">@dimen/touch_target</item>
-        <item name="android:textSize">@dimen/text_body</item>
-        <item name="android:textColor">@color/choice_text</item>
-        <item name="chipBackgroundColor">@color/choice_background</item>
-        <item name="chipStrokeColor">@color/choice_stroke</item>
-        <item name="chipStrokeWidth">1dp</item>
-        <item name="chipStartPadding">16dp</item>
-        <item name="chipEndPadding">16dp</item>
-        <item name="ensureMinTouchTargetSize">false</item>
-    </style>
 </resources>