diff --git a/docs/finalmouse-testing.md b/docs/finalmouse-testing.md
index 4b3b5772..724e50c2 100644
--- a/docs/finalmouse-testing.md
+++ b/docs/finalmouse-testing.md
@@ -31,6 +31,12 @@ was available, so every SLX path below is **unverified on hardware**:
   capture/live-stream cmds 27-30 are intentionally not wired to any UI.
 - PerfectPolling: display-only in xpanel (fixed 250 µs end-to-end claim);
   there is no writable command, so OpenMouse shows an info card.
+- Polling rate: the Starlight X has none to set — PerfectPolling runs a fixed
+  pipeline. The driver still surfaces the rate it reports for telemetry, but
+  advertises no selectable rates (`supportedPollingRates: []`), refuses
+  `setPollingRate`, and sets `pollingReadOnly` so the app hides the selector
+  (`hideMotionSync` likewise, since Motion Sync is not user-facing there).
+  Ultralight X keeps the full 500-8000 Hz ladder and its Motion Sync toggle.
 - LOD custom: PAW cmd 25. Presets send raw 2 (= 1 mm) / raw 3 (= 2 mm);
   the custom slider sends raw 7-17 (= 0.7-1.7 mm). Surfaced through the
   shared `liftOffScale` slider plus the `setLiftOffScale` driver hook.
diff --git a/src/drivers/finalmouse/hid.ts b/src/drivers/finalmouse/hid.ts
index c1f1cb33..baa15647 100644
--- a/src/drivers/finalmouse/hid.ts
+++ b/src/drivers/finalmouse/hid.ts
@@ -157,13 +157,21 @@ export class FinalmouseHidClient {
         defaultDisplayName: slx ? FINALMOUSE_SLX_DISPLAY_NAME : FINALMOUSE_DISPLAY_NAME,
         hideUnsupportedPollingRates: true,
         forceShowBattery: true,
+        // Starlight X runs PerfectPolling: a fixed-rate pipeline with no
+        // selectable polling rate and no user-facing Motion Sync, so the app
+        // must not offer either as if they were adjustable. Ultralight X
+        // exposes both.
+        pollingReadOnly: slx ? true : undefined,
+        hideMotionSync: slx ? true : undefined,
       },
       batteryPercent: state.batterySoc ?? state.batteryPercent ?? null,
       batteryVoltageMv: state.batteryVoltageMv ?? null,
       batteryState: state.chargingState === 1 ? "Charging" : state.chargingState === undefined ? "Unknown" : "Discharging",
       dpi: state.dpi,
       pollingRateHz: state.pollingRateHz,
-      supportedPollingRates: [...POLLING_RATES],
+      // Starlight X: PerfectPolling is fixed, so it advertises no selectable
+      // rates. Ultralight X lists the whole ladder.
+      supportedPollingRates: [...this.supportedPollingRates],
       activeProfile: null,
       unitId: state.mouseSerial ?? null,
       connectionType: "Wireless",
@@ -242,12 +250,23 @@ export class FinalmouseHidClient {
   }
 
   async setPollingRate(pollingRateHz: number): Promise<number> {
-    if (!(POLLING_RATES as readonly number[]).includes(pollingRateHz)) throw new Error("Unsupported Finalmouse UltralightX polling rate.");
+    const supported: readonly number[] = this.supportedPollingRates;
+    if (!supported.includes(pollingRateHz)) throw new Error("This Finalmouse dongle has no adjustable polling rate.");
     await this.writeU16(FINALMOUSE_COMMAND.pollingRate, pollingRateHz);
     this.telemetry.pollingRateHz = pollingRateHz;
     return pollingRateHz;
   }
 
+  /**
+   * Rates this dongle accepts. The Ultralight X exposes the whole ladder; the
+   * Starlight X's PerfectPolling pipeline is fixed, so it offers none. The
+   * reported `pollingRateHz` is still surfaced for telemetry, but the app
+   * hides the selector (see `pollingReadOnly`).
+   */
+  private get supportedPollingRates(): readonly number[] {
+    return this.isSlx ? [] : POLLING_RATES;
+  }
+
   async setMotionSync(enabled: boolean): Promise<boolean> {
     await this.write(this.txReport, FINALMOUSE_COMMAND.motionSync, new Uint8Array([enabled ? 1 : 0]));
     this.telemetry.motionSync = enabled;
diff --git a/src/drivers/finalmouse/protocol.test.ts b/src/drivers/finalmouse/protocol.test.ts
index bd879684..9b0e2241 100644
--- a/src/drivers/finalmouse/protocol.test.ts
+++ b/src/drivers/finalmouse/protocol.test.ts
@@ -271,3 +271,37 @@ test("Finalmouse SLX setters frame TMR, profiles and PAW LOD on report 0x01", as
   assert.deepEqual(writes[2]!.bytes.slice(0, 4), [3, 0xb9, 1, 2]);
   assert.deepEqual(writes[3]!.bytes.slice(0, 4), [3, 0x99, 1, 12]);
 });
+
+test("Finalmouse Starlight X exposes a fixed PerfectPolling rate, not a picker", async () => {
+  // SLX answers the poll-rate read (so readStatus still needs it) but has no
+  // adjustable rate, so it advertises none and refuses a write; the app then
+  // hides the selector via `pollingReadOnly` / `hideMotionSync`.
+  let listener: ((event: HIDInputReportEvent) => void) | null = null;
+  const device = {
+    vendorId: 0x361d,
+    productId: 0x0300,
+    productName: "Finalmouse SLX",
+    collections: [{ usagePage: 0xff00, usage: 1 }],
+    opened: true,
+    async open() {},
+    async close() {},
+    addEventListener(_type: string, handler: (event: HIDInputReportEvent) => void) { listener = handler; },
+    removeEventListener() {},
+    async sendReport() {},
+  } as unknown as HIDDevice;
+  const client = new FinalmouseHidClient(device);
+  // Attach the input listener before emitting, mirroring a real burst that
+  // arrives after the driver opens the interface.
+  await client.open();
+  const emit = (command: number, payload: number[]): void => {
+    listener?.({ reportId: FINALMOUSE_REPORT.slxInput, data: input(command, payload) } as HIDInputReportEvent);
+  };
+  emit(3, [0x40, 0x06]); // DPI 1600
+  emit(4, [0x40, 0x1f]); // the fixed rate the SLX reports
+
+  const status = await client.readStatus();
+  assert.deepEqual(status.supportedPollingRates, []);
+  assert.equal(status.ui?.pollingReadOnly, true);
+  assert.equal(status.ui?.hideMotionSync, true);
+  await assert.rejects(client.setPollingRate(8000), /polling rate/);
+});
diff --git a/src/drivers/finalmouse/vendors.test.ts b/src/drivers/finalmouse/vendors.test.ts
new file mode 100644
index 00000000..fbcabb76
--- /dev/null
+++ b/src/drivers/finalmouse/vendors.test.ts
@@ -0,0 +1,39 @@
+import assert from "node:assert/strict";
+import test from "node:test";
+
+import { SUPPORTED_HID_FILTERS, VENDOR_ID } from "../vendors.ts";
+import { FINALMOUSE_SLX_DONGLE_PRODUCT_IDS } from "../../finalmouse/index.ts";
+import { FinalmouseHidClient } from "./hid.ts";
+
+// Guards the picker surface: a driver that can speak a device is useless if the
+// browser picker never offers it. The ULX dongle and both Starlight X dongles
+// must each have a filter, and the SLX filters must stay usage-agnostic (only
+// the 0xff00 page is pinned) because their exact usage is not confirmed.
+test("every Finalmouse dongle the driver accepts is offered by the picker", () => {
+  const filtersFor = (productId: number) => SUPPORTED_HID_FILTERS.filter(
+    (filter) => filter.vendorId === VENDOR_ID.finalmouse && filter.productId === productId,
+  );
+
+  assert.ok(filtersFor(0x0100).length > 0, "ULX dongle 0x0100 has no filter");
+  for (const productId of FINALMOUSE_SLX_DONGLE_PRODUCT_IDS) {
+    const filters = filtersFor(productId);
+    assert.ok(filters.length > 0, `SLX dongle 0x${productId.toString(16)} has no filter`);
+    assert.ok(
+      filters.some((filter) => filter.usagePage === 0xff00 && filter.usage === undefined),
+      `SLX dongle 0x${productId.toString(16)} must match on the 0xff00 page alone`,
+    );
+  }
+});
+
+test("the Finalmouse picker filters select the dongles the client supports", () => {
+  for (const productId of [0x0100, ...FINALMOUSE_SLX_DONGLE_PRODUCT_IDS]) {
+    // Any usage inside the vendor page satisfies the filter; the driver is the
+    // thing that accepts the device, so the two must agree on the PID set.
+    const device = {
+      vendorId: VENDOR_ID.finalmouse,
+      productId,
+      collections: [{ usagePage: 0xff00, usage: productId === 0x0100 ? 0x0001 : 0x0009 }],
+    } as unknown as HIDDevice;
+    assert.equal(FinalmouseHidClient.isSupported(device), true, `0x${productId.toString(16)} not supported`);
+  }
+});
diff --git a/src/drivers/vendors.ts b/src/drivers/vendors.ts
index a7b8f047..3387e201 100644
--- a/src/drivers/vendors.ts
+++ b/src/drivers/vendors.ts
@@ -8,6 +8,7 @@ import {
 } from "../asus/index.ts";
 import { ATK_COMPX_PRODUCT_IDS } from "./atk/products.ts";
 import { MICROSOFT_PRODUCT_CLASSIC, MICROSOFT_PRODUCT_PRO, MICROSOFT_VENDOR_ID, MICROSOFT_CLASSIC_USAGE_PAGE, MICROSOFT_CLASSIC_USAGE, MICROSOFT_PRO_USAGE_PAGE, MICROSOFT_PRO_USAGE } from "../microsoft/index.ts";
+import { FINALMOUSE_SLX_DONGLE_PRODUCT_IDS } from "../finalmouse/index.ts";
 import { INCOTT_PRODUCT_IDS, INCOTT_USAGE_PAGE, INCOTT_VENDOR_ID } from "../incott/index.ts";
 import { GLORIOUS_CORE2_PRODUCTS, GLORIOUS_CORE2_USAGE_PAGE, GLORIOUS_CORE2_VENDOR_ID } from "../glorious-core2/index.ts";
 import { EGG_WE_HID_FILTERS } from "./endgame/egg-we-control.ts";
@@ -883,6 +884,13 @@ export const SUPPORTED_HID_FILTERS: HIDDeviceFilter[] = [
   ...CORSAIR_HID_FILTERS,
   ...CORSAIR_BRAGI_HID_FILTERS,
   { vendorId: VENDOR_ID.finalmouse, productId: 0x0100, usagePage: 0xff00, usage: 0x0001 },
+  // Starlight X dongles share 0xff00 but the exact usage is not pinned down, so
+  // the picker matches on the page alone (the driver accepts either).
+  ...FINALMOUSE_SLX_DONGLE_PRODUCT_IDS.map((productId) => ({
+    vendorId: VENDOR_ID.finalmouse,
+    productId,
+    usagePage: 0xff00,
+  })),
   { vendorId: VENDOR_ID.pulsar },
   ...PULSAR_XS1_HID_FILTERS,
   // The Pulsar 4K Wireless Receiver enumerates under the shared Teevolution/VGN