diff --git a/src/metrics.ts b/src/metrics.ts
index acfd2ff5..82df00c4 100644
--- a/src/metrics.ts
+++ b/src/metrics.ts
@@ -57,6 +57,7 @@ type PlatformData = {
 interface BaseMetricsData {
   appName: string;
   instanceId: string;
+  connectionId: string;
   platformName: PlatformName;
   platformVersion: string;
   yggdrasilVersion: null;
@@ -257,6 +258,7 @@ export default class Metrics extends EventEmitter {
         appName: this.appName,
         instanceId: this.instanceId,
         connectionId: this.connectionId,
+        interval: this.metricsInterval,
         headers,
         timeout: this.timeout,
         httpOptions: this.httpOptions,
@@ -360,6 +362,7 @@ export default class Metrics extends EventEmitter {
     return {
       appName: this.appName,
       instanceId: this.instanceId,
+      connectionId: this.connectionId,
       bucket,
       platformName: this.platformData.name,
       platformVersion: this.platformData.version,
@@ -394,6 +397,7 @@ export default class Metrics extends EventEmitter {
       strategies: this.strategies,
       started: this.started,
       interval: this.metricsInterval,
+      connectionId: this.connectionId,
       platformName: this.platformData.name,
       platformVersion: this.platformData.version,
       yggdrasilVersion: null,
diff --git a/src/repository/index.ts b/src/repository/index.ts
index a26a612e..90161be0 100644
--- a/src/repository/index.ts
+++ b/src/repository/index.ts
@@ -430,6 +430,7 @@ Message: ${err.message}`,
         timeout: this.timeout,
         instanceId: this.instanceId,
         connectionId: this.connectionId,
+        interval: this.refreshInterval,
         headers,
         httpOptions: this.httpOptions,
         supportedSpecVersion: SUPPORTED_SPEC_VERSION,
diff --git a/src/request.ts b/src/request.ts
index 81d8e41e..bbe40621 100644
--- a/src/request.ts
+++ b/src/request.ts
@@ -22,6 +22,7 @@ export interface GetRequestOptions extends RequestOptions {
   connectionId: string;
   supportedSpecVersion?: string;
   httpOptions?: HttpOptions;
+  interval?: number;
 }
 
 export interface Data {
@@ -33,6 +34,7 @@ export interface PostRequestOptions extends RequestOptions {
   appName?: string;
   instanceId?: string;
   connectionId?: string;
+  interval?: number;
   httpOptions?: HttpOptions;
 }
 
@@ -66,6 +68,7 @@ type HeaderOptions = {
   custom?: CustomHeaders;
   specVersionSupported?: string;
   connectionId?: string;
+  interval?: number;
 };
 
 export const buildHeaders = ({
@@ -76,6 +79,7 @@ export const buildHeaders = ({
   custom,
   specVersionSupported,
   connectionId,
+  interval,
 }: HeaderOptions): Record<string, string> => {
   const head: Record<string, string> = {};
   if (appName) {
@@ -108,6 +112,10 @@ export const buildHeaders = ({
     head['unleash-connection-id'] = connectionId;
   }
 
+  // expressed in milliseconds to match refreshInterval and metricsInterval units
+  // attach when set explicitly to non-zero value
+  head['unleash-interval'] = String(interval);
+
   return head;
 };
 
@@ -117,6 +125,7 @@ export const post = ({
   timeout,
   instanceId,
   connectionId,
+  interval,
   headers,
   json,
   httpOptions,
@@ -129,6 +138,7 @@ export const post = ({
       appName,
       instanceId,
       connectionId,
+      interval,
       etag: undefined,
       contentType: 'application/json',
       custom: headers,
@@ -144,6 +154,7 @@ export const get = ({
   timeout,
   instanceId,
   connectionId,
+  interval,
   headers,
   httpOptions,
   supportedSpecVersion,
@@ -155,6 +166,7 @@ export const get = ({
     headers: buildHeaders({
       appName,
       instanceId,
+      interval,
       etag,
       contentType: undefined,
       custom: headers,
diff --git a/src/test/metrics.test.ts b/src/test/metrics.test.ts
index a9f2c817..2fda443b 100644
--- a/src/test/metrics.test.ts
+++ b/src/test/metrics.test.ts
@@ -89,7 +89,7 @@ test('should sendMetrics and register when metricsInterval is a positive number'
 
 test('should sendMetrics', async (t) => {
   const url = getUrl();
-  t.plan(6);
+  t.plan(7);
   const metricsEP = nock(url)
     .post(metricsUrl, (payload) => {
       t.truthy(payload.bucket);
@@ -99,6 +99,7 @@ test('should sendMetrics', async (t) => {
         'toggle-x': { yes: 1, no: 1, variants: { 'variant-a': 2 } },
         'toggle-y': { yes: 1, no: 0, variants: {} },
       });
+      t.deepEqual(payload.connectionId, 'connection-id');
       return true;
     })
     .reply(200, '');
@@ -108,6 +109,7 @@ test('should sendMetrics', async (t) => {
   const metrics = new Metrics({
     url,
     metricsInterval: 50,
+    connectionId: 'connection-id',
   });
 
   metrics.count('toggle-x', true);
@@ -131,7 +133,8 @@ test('should send correct custom and unleash headers', (t) =>
       .matchHeader('randomKey', randomKey)
       .matchHeader('unleash-appname', 'appName')
       .matchHeader('unleash-sdk', /^unleash-client-node:\d+\.\d+\.\d+/)
-      .matchHeader('unleash-connection-id', 'connectionId');
+      .matchHeader('unleash-connection-id', 'connectionId')
+      .matchHeader('unleash-interval', '50');
     const regEP = nockRegister(url)
       .matchHeader('randomKey', randomKey)
       .matchHeader('unleash-appname', 'appName')
@@ -578,6 +581,7 @@ test('getClientData should include extended metrics', (t) => {
   // @ts-expect-error
   const metrics = new Metrics({
     url,
+    connectionId: 'connection-id',
   });
   metrics.start();
 
@@ -586,6 +590,7 @@ test('getClientData should include extended metrics', (t) => {
   t.truthy(result.platformVersion);
   t.true(result.yggdrasilVersion === null);
   t.true(result.specVersion === SUPPORTED_SPEC_VERSION);
+  t.deepEqual(result.connectionId, 'connection-id');
 });
 
 test('createMetricsData should include extended metrics', (t) => {
diff --git a/src/test/repository.test.ts b/src/test/repository.test.ts
index ff2de4f2..a3fd63c2 100644
--- a/src/test/repository.test.ts
+++ b/src/test/repository.test.ts
@@ -197,6 +197,7 @@ test('should request with correct custom and unleash headers', (t) =>
       .matchHeader('randomKey', randomKey)
       .matchHeader('unleash-appname', appName)
       .matchHeader('unleash-connection-id', connectionId)
+      .matchHeader('unleash-interval', '10')
       .matchHeader('unleash-sdk', /^unleash-client-node:\d+\.\d+\.\d+/)
       .persist()
       .get('/client/features')
@@ -214,6 +215,7 @@ test('should request with correct custom and unleash headers', (t) =>
       headers: {
         randomKey,
         'unleash-connection-id': 'ignore',
+        'unleash-interval': 'ignore',
       },
       mode: { type: 'polling', format: 'full' },
     });
diff --git a/src/test/request.test.ts b/src/test/request.test.ts
index e178dc42..9cc3250f 100644
--- a/src/test/request.test.ts
+++ b/src/test/request.test.ts
@@ -21,6 +21,7 @@ test('Correct headers should be included', (t) => {
     etag: undefined,
     contentType: undefined,
     connectionId: 'connectionId',
+    interval: 10000,
     custom: {
       hello: 'world',
     },
@@ -28,6 +29,7 @@ test('Correct headers should be included', (t) => {
   t.is(headers.hello, 'world');
   t.is(headers['UNLEASH-INSTANCEID'], 'instanceId');
   t.is(headers['unleash-connection-id'], 'connectionId');
+  t.is(headers['unleash-interval'], '10000');
   t.is(headers['unleash-appname'], 'myApp');
   t.regex(headers['unleash-sdk'], /^unleash-client-node:\d+\.\d+\.\d+/);
 });