diff --git a/src/app/cards/PerformanceCards.tsx b/src/app/cards/PerformanceCards.tsx
index accfa0dc..ef882e13 100644
--- a/src/app/cards/PerformanceCards.tsx
+++ b/src/app/cards/PerformanceCards.tsx
@@ -7,6 +7,7 @@ import {
 } from "@openmouse/protocol/drivers/logitech/onboard-profiles";
 import * as control from "../../device/controller";
 import { isNoirKsnakeStatus } from "../../device/noir.ts";
+import { pollingRateText } from "../../ui/polling-rate";
 import { isNativeAttackSharkX11, RATE_STEPS_HZ } from "../../device/controller";
 import type { ControlSnapshot, LiftOffLevel } from "../../device/types";
 import { t, tp } from "../../i18n";
@@ -66,7 +67,7 @@ export function PollingCard({ snapshot }: { snapshot: ControlSnapshot }): ReactN
           <small id="polling-note" className="setting-note">{note}</small>
         </div>
         {!perProfile ? (
-          <output id="polling-value">{status.pollingRateHz.toLocaleString()} Hz</output>
+          <output id="polling-value">{pollingRateText(status.pollingRateHz)} Hz</output>
         ) : null}
       </div>
 
diff --git a/src/app/ui.tsx b/src/app/ui.tsx
index 9f8e5aff..10479cd6 100644
--- a/src/app/ui.tsx
+++ b/src/app/ui.tsx
@@ -2,6 +2,7 @@ import { useEffect, useId, useRef, useState, type ReactNode } from "react";
 import { Check, ChevronDown, Minus, Plus } from "lucide-react";
 import type { MouseStatus } from "@openmouse/protocol/drivers/mouse-types";
 import { batteryFillWidth, batteryIconState, batteryLevel } from "../ui/battery-icon";
+import { selectedPollingStep } from "../ui/polling-rate";
 import { t } from "../i18n";
 import type { InterfaceLocale } from "../interface-preferences";
 
@@ -387,22 +388,14 @@ export function RateSlider({
   bubble?: boolean;
 }): ReactNode {
   if (options.length === 0) return <div id={id} className="rate-slider" hidden={hidden} />;
-  const selected = valueHz !== null && options.includes(valueHz)
-    ? options.indexOf(valueHz)
-    : options.reduce(
-      (best, rate, step) =>
-        Math.abs(rate - (valueHz ?? options[0] ?? 0)) < Math.abs((options[best] ?? 0) - (valueHz ?? options[0] ?? 0))
-          ? step
-          : best,
-      0,
-    );
+  const selected = selectedPollingStep(options, valueHz);
 
   return (
     <div id={id} className="rate-slider" hidden={hidden}>
       {label ? (
         <div className="rate-slider-head">
           <span>{label}</span>
-          <output>{options[selected]?.toLocaleString() ?? "—"} Hz</output>
+          <output>{selected === null ? "—" : options[selected]?.toLocaleString() ?? "—"} Hz</output>
         </div>
       ) : null}
       <div className="rate-slider-buttons" role="group" aria-label={label ?? t(locale, "perf.reportRate")}>
@@ -423,7 +416,7 @@ export function RateSlider({
           );
         })}
       </div>
-      {hoursAt?.(options[selected] ?? 0) != null ? (
+      {selected !== null && hoursAt?.(options[selected] ?? 0) != null ? (
         <small className="rate-slider-hours">
           About {Math.round(hoursAt?.(options[selected] ?? 0) as number)} h per full charge at {options[selected]?.toLocaleString()} Hz
         </small>
diff --git a/src/device/controller.ts b/src/device/controller.ts
index 5b7baa4d..f8938399 100644
--- a/src/device/controller.ts
+++ b/src/device/controller.ts
@@ -1,5 +1,6 @@
 import { cachedBatterySamples, estimateBatteryTime, estimateFromRatedLife, ratedBattery, recordBatterySample, type BatteryMode } from "../battery-history";
 import { applyBridgeNativeSettings } from "../bridge";
+import { pollingRateText } from "../ui/polling-rate";
 import {
   clientSupportScore,
   createSupportedClient,
@@ -2348,10 +2349,10 @@ function applyStatusInner(deviceStatus: MouseStatus, statusKey?: string): void {
       ? st("ctl.connected")
       : st("ctl.batteryPct", { n: deviceStatus.batteryPercent });
     readStatus = status.ui?.valuesVerified
-      ? [summary, `${deviceStatus.dpi.toLocaleString()} DPI`, `${deviceStatus.pollingRateHz.toLocaleString()} Hz`].join(" · ")
+      ? [summary, `${deviceStatus.dpi.toLocaleString()} DPI`, `${pollingRateText(deviceStatus.pollingRateHz)} Hz`].join(" · ")
       : summary;
   } else if (!hasPendingChanges()) {
-    readStatus = st("ctl.currentLine", { dpi: deviceStatus.dpi.toLocaleString(), hz: deviceStatus.pollingRateHz.toLocaleString() });
+    readStatus = st("ctl.currentLine", { dpi: deviceStatus.dpi.toLocaleString(), hz: pollingRateText(deviceStatus.pollingRateHz) });
   }
 
   if (!customDpiEditing) customDpiText = `${status.dpi.toLocaleString()} DPI`;
diff --git a/src/preview-fixtures.ts b/src/preview-fixtures.ts
index 0a653a9b..f503f241 100644
--- a/src/preview-fixtures.ts
+++ b/src/preview-fixtures.ts
@@ -43,6 +43,34 @@ const PULSAR: MouseStatus = {
   firmware: ["1.04.11"],
 };
 
+const PULSAR_XS1_8K: MouseStatus = {
+  ...PULSAR,
+  name: "Pulsar 8K Dongle",
+  ui: {
+    family: "pulsar",
+    hideUnsupportedPollingRates: true,
+    pollingReadOnly: true,
+    pollingNote: "The XS-1 polling readout is not hardware-verified. Polling changes are unavailable; check the rate in Pulsar's software.",
+    hideSleepCard: true,
+    hideSignalCard: true,
+    forceShowBattery: true,
+  },
+  pollingRateHz: 8000,
+  supportedPollingRates: [125, 250, 500, 1000, 2000, 4000, 8000],
+  activeProfile: null,
+  dongleLedEnabled: undefined,
+  connectionDetail: "XS-1 feature-report interface",
+};
+
+const PULSAR_XS1_UNKNOWN: MouseStatus = {
+  ...PULSAR_XS1_8K,
+  pollingRateHz: 0,
+  ui: {
+    ...PULSAR_XS1_8K.ui,
+    pollingNote: "The XS-1 interface did not return a recognized polling rate. Polling changes are unavailable; check the rate in Pulsar's software.",
+  },
+};
+
 const PULSAR_PRO: MouseStatus = {
   ...PULSAR,
   name: "Pulsar X2 V2 Pro",
@@ -848,6 +876,8 @@ const RAWM_V4_GT: MouseStatus = {
 export const PREVIEW_FIXTURES: Record<FixturePreviewMode, PreviewFixture> = {
   pulsar: { label: "Pulsar X2 V2", status: PULSAR },
   "pulsar-pro": { label: "Pulsar X2 V2 Pro", status: PULSAR_PRO },
+  "pulsar-xs1-8k": { label: "Pulsar XS-1 8K dongle", status: PULSAR_XS1_8K },
+  "pulsar-xs1-unknown": { label: "Pulsar XS-1 unknown polling", status: PULSAR_XS1_UNKNOWN },
   "egg-op1": { label: "Endgame Gear OP1 8K", status: EGG_OP1 },
   "egg-we": { label: "Endgame Gear OP1we", status: EGG_WE },
   "egg-xm2we": { label: "Endgame Gear XM2we", status: EGG_XM2WE },
diff --git a/src/preview-modes.ts b/src/preview-modes.ts
index a33c3c25..3c521b3b 100644
--- a/src/preview-modes.ts
+++ b/src/preview-modes.ts
@@ -10,6 +10,8 @@ export const PREVIEW_KEYS = [
   "superstrike",
   "pulsar",
   "pulsar-pro",
+  "pulsar-xs1-8k",
+  "pulsar-xs1-unknown",
   "egg-op1",
   "egg-we",
   "egg-xm2we",
@@ -55,6 +57,8 @@ export function parsePreviewMode(value: string | null): PreviewMode | null {
     case "superstrike": return "superstrike";
     case "pulsar": return "pulsar";
     case "pulsar-pro": return "pulsar-pro";
+    case "pulsar-xs1-8k": return "pulsar-xs1-8k";
+    case "pulsar-xs1-unknown": return "pulsar-xs1-unknown";
     case "egg-op1": return "egg-op1";
     case "egg-we": return "egg-we";
     case "egg-xm2we": return "egg-xm2we";
diff --git a/src/ui/polling-rate.test.ts b/src/ui/polling-rate.test.ts
new file mode 100644
index 00000000..4cd0dc53
--- /dev/null
+++ b/src/ui/polling-rate.test.ts
@@ -0,0 +1,21 @@
+import assert from "node:assert/strict";
+import test from "node:test";
+import { pollingRateText, selectedPollingStep } from "./polling-rate.ts";
+
+const RATES = [125, 250, 500, 1000, 2000, 4000, 8000];
+
+test("unavailable driver rates display a dash and never select the 125 Hz button", () => {
+  for (const value of [0, -1, NaN, Infinity]) {
+    assert.equal(pollingRateText(value), "—");
+    assert.equal(selectedPollingStep(RATES, value), null);
+  }
+  assert.equal(selectedPollingStep(RATES, null), null);
+});
+
+test("8K polling can select its real step and known off-grid rates keep nearest-step behavior", () => {
+  assert.equal(selectedPollingStep(RATES, 8000), 6);
+  assert.equal(selectedPollingStep(RATES, 1000), 3);
+  assert.equal(selectedPollingStep(RATES, 750), 2);
+  assert.equal(selectedPollingStep([], 1000), null);
+  assert.notEqual(pollingRateText(8000), "—");
+});
diff --git a/src/ui/polling-rate.ts b/src/ui/polling-rate.ts
new file mode 100644
index 00000000..680f4681
--- /dev/null
+++ b/src/ui/polling-rate.ts
@@ -0,0 +1,13 @@
+/** Zero/non-finite rates represent a missing hardware read, not a setting. */
+export function pollingRateText(rate: number): string {
+  return Number.isFinite(rate) && rate > 0 ? rate.toLocaleString() : "—";
+}
+
+/** Preserve nearest-step selection for known rates; leave unknown ones blank. */
+export function selectedPollingStep(options: readonly number[], rate: number | null): number | null {
+  if (options.length === 0 || rate === null || !Number.isFinite(rate) || rate <= 0) return null;
+  const exact = options.indexOf(rate);
+  if (exact >= 0) return exact;
+  return options.reduce((best, candidate, index) =>
+    Math.abs(candidate - rate) < Math.abs(options[best]! - rate) ? index : best, 0);
+}