diff --git a/packages/operators/src/request.test.js b/packages/operators/src/request.test.js
index 9c0d82a..85adbfd 100644
--- a/packages/operators/src/request.test.js
+++ b/packages/operators/src/request.test.js
@@ -9,10 +9,10 @@ import { test, describe, beforeEach, expect, vi, afterAll, beforeAll } from 'vit
 
 import { log, logResult } from './log.js';
 import { resolveBlob, resolveJSON } from './response.js';
-import { EstimateTime } from './stream/observables/EstimateTime.js';
-import { Progress } from './stream/observables/Progress.js';
-import { TransferRate } from './stream/observables/TransferRate.js';
-import { MBYTE, SECOND } from './stream/observables/utils.js';
+import { EstimateTime } from './stream/stats/EstimateTime.js';
+import { Progress } from './stream/stats/Progress.js';
+import { TransferRate } from './stream/stats/TransferRate.js';
+import { MBYTE, SECOND } from './stream/stats/utils.js';
 
 describe.skip('request', () => {
   let testScheduler;
@@ -176,13 +176,13 @@ describe.skip('request - demo ', () => {
       body: formData
     });
 
-    const progressUpload = Progress();
+    const progressUpload = new Progress();
     progressUpload.subscribe({
       next: e => console.log('UPLOAD', e),
       complete: () => console.log('complete')
     });
 
-    const progressDownload = Progress();
+    const progressDownload = new Progress();
     progressDownload.subscribe({
       next: e => console.log('DOWNLOAD', e),
       complete: () => console.log('complete')
@@ -205,13 +205,13 @@ describe('test', () => {
   test('progress on download', async () => {
     const { request } = await import('./request.js');
 
-    const progress = Progress();
+    const progress = new Progress();
     progress.subscribe({ next: e => console.log('DOWNLOAD', e) });
 
-    const byteRate = TransferRate(MBYTE, SECOND);
+    const byteRate = new TransferRate(MBYTE, SECOND);
     byteRate.subscribe({ next: e => console.log('RATE', e) });
 
-    const estimateTime = EstimateTime(SECOND);
+    const estimateTime = new EstimateTime(SECOND);
     estimateTime.subscribe({ next: e => console.log('ESTIMATE', e) });
 
     const fileMap = {
diff --git a/packages/operators/src/stream/observables/EstimateTime.js b/packages/operators/src/stream/stats/EstimateTime.js
similarity index 59%
rename from packages/operators/src/stream/observables/EstimateTime.js
rename to packages/operators/src/stream/stats/EstimateTime.js
index 1891a51..de19caf 100644
--- a/packages/operators/src/stream/observables/EstimateTime.js
+++ b/packages/operators/src/stream/stats/EstimateTime.js
@@ -2,15 +2,18 @@ import { concatWith, distinctUntilChanged, map, of, Subject } from 'rxjs';
 
 import { calcReceivedStats, MSECOND } from './utils';
 
-export const EstimateTime = (timeUnit = MSECOND) => {
-  return new Subject().pipe(
-    calcReceivedStats(),
-    calcEstimatedTime(),
-    concatWith(of(0)),
-    distinctUntilChanged(),
-    convertEstimedTimeTo(timeUnit)
-  );
-};
+export class EstimateTime extends Subject {
+  constructor(timeUnit = MSECOND) {
+    super();
+    return this.pipe(
+      calcReceivedStats(),
+      calcEstimatedTime(),
+      concatWith(of(0)),
+      distinctUntilChanged(),
+      convertEstimedTimeTo(timeUnit)
+    );
+  }
+}
 
 const calcEstimatedTime = () => {
   return source =>
diff --git a/packages/operators/src/stream/observables/Progress.js b/packages/operators/src/stream/stats/Progress.js
similarity index 53%
rename from packages/operators/src/stream/observables/Progress.js
rename to packages/operators/src/stream/stats/Progress.js
index 31082b0..6c1d2e5 100644
--- a/packages/operators/src/stream/observables/Progress.js
+++ b/packages/operators/src/stream/stats/Progress.js
@@ -2,14 +2,17 @@ import { concatWith, distinctUntilChanged, map, of, Subject } from 'rxjs';
 
 import { calcReceivedStats } from './utils';
 
-export const Progress = () => {
-  return new Subject().pipe(
-    calcReceivedStats(),
-    calcPercentageProgress(),
-    concatWith(of(100)),
-    distinctUntilChanged()
-  );
-};
+export class Progress extends Subject {
+  constructor() {
+    super();
+    return this.pipe(
+      calcReceivedStats(),
+      calcPercentageProgress(),
+      concatWith(of(100)),
+      distinctUntilChanged()
+    );
+  }
+}
 
 const calcPercentageProgress = () => {
   return source => source.pipe(map(({ value, total }) => Math.floor((value / total) * 100)));
diff --git a/packages/operators/src/stream/observables/TransferRate.js b/packages/operators/src/stream/stats/TransferRate.js
similarity index 58%
rename from packages/operators/src/stream/observables/TransferRate.js
rename to packages/operators/src/stream/stats/TransferRate.js
index 71e105e..a1c42e5 100644
--- a/packages/operators/src/stream/observables/TransferRate.js
+++ b/packages/operators/src/stream/stats/TransferRate.js
@@ -2,13 +2,16 @@ import { map, Subject } from 'rxjs';
 
 import { calcReceivedStats, MBIT, SECOND } from './utils';
 
-export const TransferRate = (byteUnit = MBIT, timeUnit = SECOND) => {
-  return new Subject().pipe(
-    calcReceivedStats(),
-    calcAverageByteLengthPerTimeUnit(timeUnit),
-    calcTransferRate(byteUnit)
-  );
-};
+export class TransferRate extends Subject {
+  constructor(byteUnit = MBIT, timeUnit = SECOND) {
+    super();
+    return this.pipe(
+      calcReceivedStats(),
+      calcAverageByteLengthPerTimeUnit(timeUnit),
+      calcTransferRate(byteUnit)
+    );
+  }
+}
 
 const calcAverageByteLengthPerTimeUnit = timeRatio => {
   return source => source.pipe(map(({ value, period }) => (value / period) * timeRatio));
diff --git a/packages/operators/src/stream/observables/utils.js b/packages/operators/src/stream/stats/utils.js
similarity index 100%
rename from packages/operators/src/stream/observables/utils.js
rename to packages/operators/src/stream/stats/utils.js