diff --git a/baselines/asset/src/v1/asset_service_client.ts.baseline b/baselines/asset/src/v1/asset_service_client.ts.baseline
index 886f8b269..d30a22548 100644
--- a/baselines/asset/src/v1/asset_service_client.ts.baseline
+++ b/baselines/asset/src/v1/asset_service_client.ts.baseline
@@ -132,6 +132,8 @@ export class AssetServiceClient {
     }
     if (!opts.fallback) {
       clientHeader.push(`grpc/${this._gaxGrpc.grpcVersion}`);
+    } else if (opts.fallback === 'rest' ) {
+      clientHeader.push(`rest/${this._gaxGrpc.grpcVersion}`);
     }
     if (opts.libName && opts.libVersion) {
       clientHeader.push(`${opts.libName}/${opts.libVersion}`);
diff --git a/baselines/bigquery-storage/src/v1beta1/big_query_storage_client.ts.baseline b/baselines/bigquery-storage/src/v1beta1/big_query_storage_client.ts.baseline
index 0f457aee9..138aba84f 100644
--- a/baselines/bigquery-storage/src/v1beta1/big_query_storage_client.ts.baseline
+++ b/baselines/bigquery-storage/src/v1beta1/big_query_storage_client.ts.baseline
@@ -133,6 +133,8 @@ export class BigQueryStorageClient {
     }
     if (!opts.fallback) {
       clientHeader.push(`grpc/${this._gaxGrpc.grpcVersion}`);
+    } else if (opts.fallback === 'rest' ) {
+      clientHeader.push(`rest/${this._gaxGrpc.grpcVersion}`);
     }
     if (opts.libName && opts.libVersion) {
       clientHeader.push(`${opts.libName}/${opts.libVersion}`);
diff --git a/baselines/disable-packing-test/src/v1beta1/echo_client.ts.baseline b/baselines/disable-packing-test/src/v1beta1/echo_client.ts.baseline
index 49291499f..2b4e63c69 100644
--- a/baselines/disable-packing-test/src/v1beta1/echo_client.ts.baseline
+++ b/baselines/disable-packing-test/src/v1beta1/echo_client.ts.baseline
@@ -138,6 +138,8 @@ export class EchoClient {
     }
     if (!opts.fallback) {
       clientHeader.push(`grpc/${this._gaxGrpc.grpcVersion}`);
+    } else if (opts.fallback === 'rest' ) {
+      clientHeader.push(`rest/${this._gaxGrpc.grpcVersion}`);
     }
     if (opts.libName && opts.libVersion) {
       clientHeader.push(`${opts.libName}/${opts.libVersion}`);
diff --git a/baselines/disable-packing-test/src/v1beta1/identity_client.ts.baseline b/baselines/disable-packing-test/src/v1beta1/identity_client.ts.baseline
index 0dc2e7512..fde9f6127 100644
--- a/baselines/disable-packing-test/src/v1beta1/identity_client.ts.baseline
+++ b/baselines/disable-packing-test/src/v1beta1/identity_client.ts.baseline
@@ -133,6 +133,8 @@ export class IdentityClient {
     }
     if (!opts.fallback) {
       clientHeader.push(`grpc/${this._gaxGrpc.grpcVersion}`);
+    } else if (opts.fallback === 'rest' ) {
+      clientHeader.push(`rest/${this._gaxGrpc.grpcVersion}`);
     }
     if (opts.libName && opts.libVersion) {
       clientHeader.push(`${opts.libName}/${opts.libVersion}`);
diff --git a/baselines/disable-packing-test/src/v1beta1/messaging_client.ts.baseline b/baselines/disable-packing-test/src/v1beta1/messaging_client.ts.baseline
index 42a3d6113..a065a9e10 100644
--- a/baselines/disable-packing-test/src/v1beta1/messaging_client.ts.baseline
+++ b/baselines/disable-packing-test/src/v1beta1/messaging_client.ts.baseline
@@ -137,6 +137,8 @@ export class MessagingClient {
     }
     if (!opts.fallback) {
       clientHeader.push(`grpc/${this._gaxGrpc.grpcVersion}`);
+    } else if (opts.fallback === 'rest' ) {
+      clientHeader.push(`rest/${this._gaxGrpc.grpcVersion}`);
     }
     if (opts.libName && opts.libVersion) {
       clientHeader.push(`${opts.libName}/${opts.libVersion}`);
diff --git a/baselines/disable-packing-test/src/v1beta1/testing_client.ts.baseline b/baselines/disable-packing-test/src/v1beta1/testing_client.ts.baseline
index 9b50f4d95..6bb455c8a 100644
--- a/baselines/disable-packing-test/src/v1beta1/testing_client.ts.baseline
+++ b/baselines/disable-packing-test/src/v1beta1/testing_client.ts.baseline
@@ -134,6 +134,8 @@ export class TestingClient {
     }
     if (!opts.fallback) {
       clientHeader.push(`grpc/${this._gaxGrpc.grpcVersion}`);
+    } else if (opts.fallback === 'rest' ) {
+      clientHeader.push(`rest/${this._gaxGrpc.grpcVersion}`);
     }
     if (opts.libName && opts.libVersion) {
       clientHeader.push(`${opts.libName}/${opts.libVersion}`);
diff --git a/baselines/dlp/src/v2/dlp_service_client.ts.baseline b/baselines/dlp/src/v2/dlp_service_client.ts.baseline
index 7495c728d..e0daf10ef 100644
--- a/baselines/dlp/src/v2/dlp_service_client.ts.baseline
+++ b/baselines/dlp/src/v2/dlp_service_client.ts.baseline
@@ -141,6 +141,8 @@ export class DlpServiceClient {
     }
     if (!opts.fallback) {
       clientHeader.push(`grpc/${this._gaxGrpc.grpcVersion}`);
+    } else if (opts.fallback === 'rest' ) {
+      clientHeader.push(`rest/${this._gaxGrpc.grpcVersion}`);
     }
     if (opts.libName && opts.libVersion) {
       clientHeader.push(`${opts.libName}/${opts.libVersion}`);
diff --git a/baselines/kms/src/v1/key_management_service_client.ts.baseline b/baselines/kms/src/v1/key_management_service_client.ts.baseline
index ac9d86afd..dcca14397 100644
--- a/baselines/kms/src/v1/key_management_service_client.ts.baseline
+++ b/baselines/kms/src/v1/key_management_service_client.ts.baseline
@@ -145,6 +145,8 @@ export class KeyManagementServiceClient {
     }
     if (!opts.fallback) {
       clientHeader.push(`grpc/${this._gaxGrpc.grpcVersion}`);
+    } else if (opts.fallback === 'rest' ) {
+      clientHeader.push(`rest/${this._gaxGrpc.grpcVersion}`);
     }
     if (opts.libName && opts.libVersion) {
       clientHeader.push(`${opts.libName}/${opts.libVersion}`);
diff --git a/baselines/logging/src/v2/config_service_v2_client.ts.baseline b/baselines/logging/src/v2/config_service_v2_client.ts.baseline
index 45d8443d4..541a1bf2f 100644
--- a/baselines/logging/src/v2/config_service_v2_client.ts.baseline
+++ b/baselines/logging/src/v2/config_service_v2_client.ts.baseline
@@ -133,6 +133,8 @@ export class ConfigServiceV2Client {
     }
     if (!opts.fallback) {
       clientHeader.push(`grpc/${this._gaxGrpc.grpcVersion}`);
+    } else if (opts.fallback === 'rest' ) {
+      clientHeader.push(`rest/${this._gaxGrpc.grpcVersion}`);
     }
     if (opts.libName && opts.libVersion) {
       clientHeader.push(`${opts.libName}/${opts.libVersion}`);
diff --git a/baselines/logging/src/v2/logging_service_v2_client.ts.baseline b/baselines/logging/src/v2/logging_service_v2_client.ts.baseline
index 46ef1bab6..09acdc057 100644
--- a/baselines/logging/src/v2/logging_service_v2_client.ts.baseline
+++ b/baselines/logging/src/v2/logging_service_v2_client.ts.baseline
@@ -133,6 +133,8 @@ export class LoggingServiceV2Client {
     }
     if (!opts.fallback) {
       clientHeader.push(`grpc/${this._gaxGrpc.grpcVersion}`);
+    } else if (opts.fallback === 'rest' ) {
+      clientHeader.push(`rest/${this._gaxGrpc.grpcVersion}`);
     }
     if (opts.libName && opts.libVersion) {
       clientHeader.push(`${opts.libName}/${opts.libVersion}`);
diff --git a/baselines/logging/src/v2/metrics_service_v2_client.ts.baseline b/baselines/logging/src/v2/metrics_service_v2_client.ts.baseline
index fbcb720f9..87f3322b7 100644
--- a/baselines/logging/src/v2/metrics_service_v2_client.ts.baseline
+++ b/baselines/logging/src/v2/metrics_service_v2_client.ts.baseline
@@ -133,6 +133,8 @@ export class MetricsServiceV2Client {
     }
     if (!opts.fallback) {
       clientHeader.push(`grpc/${this._gaxGrpc.grpcVersion}`);
+    } else if (opts.fallback === 'rest' ) {
+      clientHeader.push(`rest/${this._gaxGrpc.grpcVersion}`);
     }
     if (opts.libName && opts.libVersion) {
       clientHeader.push(`${opts.libName}/${opts.libVersion}`);
diff --git a/baselines/monitoring/src/v3/alert_policy_service_client.ts.baseline b/baselines/monitoring/src/v3/alert_policy_service_client.ts.baseline
index 10f13ea05..593f3f14c 100644
--- a/baselines/monitoring/src/v3/alert_policy_service_client.ts.baseline
+++ b/baselines/monitoring/src/v3/alert_policy_service_client.ts.baseline
@@ -141,6 +141,8 @@ export class AlertPolicyServiceClient {
     }
     if (!opts.fallback) {
       clientHeader.push(`grpc/${this._gaxGrpc.grpcVersion}`);
+    } else if (opts.fallback === 'rest' ) {
+      clientHeader.push(`rest/${this._gaxGrpc.grpcVersion}`);
     }
     if (opts.libName && opts.libVersion) {
       clientHeader.push(`${opts.libName}/${opts.libVersion}`);
diff --git a/baselines/monitoring/src/v3/group_service_client.ts.baseline b/baselines/monitoring/src/v3/group_service_client.ts.baseline
index a2db1c19f..ec67c8096 100644
--- a/baselines/monitoring/src/v3/group_service_client.ts.baseline
+++ b/baselines/monitoring/src/v3/group_service_client.ts.baseline
@@ -144,6 +144,8 @@ export class GroupServiceClient {
     }
     if (!opts.fallback) {
       clientHeader.push(`grpc/${this._gaxGrpc.grpcVersion}`);
+    } else if (opts.fallback === 'rest' ) {
+      clientHeader.push(`rest/${this._gaxGrpc.grpcVersion}`);
     }
     if (opts.libName && opts.libVersion) {
       clientHeader.push(`${opts.libName}/${opts.libVersion}`);
diff --git a/baselines/monitoring/src/v3/metric_service_client.ts.baseline b/baselines/monitoring/src/v3/metric_service_client.ts.baseline
index d0b6a1eb7..d369b7c65 100644
--- a/baselines/monitoring/src/v3/metric_service_client.ts.baseline
+++ b/baselines/monitoring/src/v3/metric_service_client.ts.baseline
@@ -134,6 +134,8 @@ export class MetricServiceClient {
     }
     if (!opts.fallback) {
       clientHeader.push(`grpc/${this._gaxGrpc.grpcVersion}`);
+    } else if (opts.fallback === 'rest' ) {
+      clientHeader.push(`rest/${this._gaxGrpc.grpcVersion}`);
     }
     if (opts.libName && opts.libVersion) {
       clientHeader.push(`${opts.libName}/${opts.libVersion}`);
diff --git a/baselines/monitoring/src/v3/notification_channel_service_client.ts.baseline b/baselines/monitoring/src/v3/notification_channel_service_client.ts.baseline
index 17c1f44ca..28fdc438b 100644
--- a/baselines/monitoring/src/v3/notification_channel_service_client.ts.baseline
+++ b/baselines/monitoring/src/v3/notification_channel_service_client.ts.baseline
@@ -134,6 +134,8 @@ export class NotificationChannelServiceClient {
     }
     if (!opts.fallback) {
       clientHeader.push(`grpc/${this._gaxGrpc.grpcVersion}`);
+    } else if (opts.fallback === 'rest' ) {
+      clientHeader.push(`rest/${this._gaxGrpc.grpcVersion}`);
     }
     if (opts.libName && opts.libVersion) {
       clientHeader.push(`${opts.libName}/${opts.libVersion}`);
diff --git a/baselines/monitoring/src/v3/service_monitoring_service_client.ts.baseline b/baselines/monitoring/src/v3/service_monitoring_service_client.ts.baseline
index 00e1004c5..08bcee238 100644
--- a/baselines/monitoring/src/v3/service_monitoring_service_client.ts.baseline
+++ b/baselines/monitoring/src/v3/service_monitoring_service_client.ts.baseline
@@ -136,6 +136,8 @@ export class ServiceMonitoringServiceClient {
     }
     if (!opts.fallback) {
       clientHeader.push(`grpc/${this._gaxGrpc.grpcVersion}`);
+    } else if (opts.fallback === 'rest' ) {
+      clientHeader.push(`rest/${this._gaxGrpc.grpcVersion}`);
     }
     if (opts.libName && opts.libVersion) {
       clientHeader.push(`${opts.libName}/${opts.libVersion}`);
diff --git a/baselines/monitoring/src/v3/uptime_check_service_client.ts.baseline b/baselines/monitoring/src/v3/uptime_check_service_client.ts.baseline
index 6c9358947..ee9cf6a15 100644
--- a/baselines/monitoring/src/v3/uptime_check_service_client.ts.baseline
+++ b/baselines/monitoring/src/v3/uptime_check_service_client.ts.baseline
@@ -140,6 +140,8 @@ export class UptimeCheckServiceClient {
     }
     if (!opts.fallback) {
       clientHeader.push(`grpc/${this._gaxGrpc.grpcVersion}`);
+    } else if (opts.fallback === 'rest' ) {
+      clientHeader.push(`rest/${this._gaxGrpc.grpcVersion}`);
     }
     if (opts.libName && opts.libVersion) {
       clientHeader.push(`${opts.libName}/${opts.libVersion}`);
diff --git a/baselines/naming/src/v1beta1/naming_client.ts.baseline b/baselines/naming/src/v1beta1/naming_client.ts.baseline
index c1159ac64..dbf314602 100644
--- a/baselines/naming/src/v1beta1/naming_client.ts.baseline
+++ b/baselines/naming/src/v1beta1/naming_client.ts.baseline
@@ -133,6 +133,8 @@ export class NamingClient {
     }
     if (!opts.fallback) {
       clientHeader.push(`grpc/${this._gaxGrpc.grpcVersion}`);
+    } else if (opts.fallback === 'rest' ) {
+      clientHeader.push(`rest/${this._gaxGrpc.grpcVersion}`);
     }
     if (opts.libName && opts.libVersion) {
       clientHeader.push(`${opts.libName}/${opts.libVersion}`);
diff --git a/baselines/redis/src/v1beta1/cloud_redis_client.ts.baseline b/baselines/redis/src/v1beta1/cloud_redis_client.ts.baseline
index a972b6927..a3964632a 100644
--- a/baselines/redis/src/v1beta1/cloud_redis_client.ts.baseline
+++ b/baselines/redis/src/v1beta1/cloud_redis_client.ts.baseline
@@ -148,6 +148,8 @@ export class CloudRedisClient {
     }
     if (!opts.fallback) {
       clientHeader.push(`grpc/${this._gaxGrpc.grpcVersion}`);
+    } else if (opts.fallback === 'rest' ) {
+      clientHeader.push(`rest/${this._gaxGrpc.grpcVersion}`);
     }
     if (opts.libName && opts.libVersion) {
       clientHeader.push(`${opts.libName}/${opts.libVersion}`);
diff --git a/baselines/showcase/src/v1beta1/echo_client.ts.baseline b/baselines/showcase/src/v1beta1/echo_client.ts.baseline
index 49291499f..2b4e63c69 100644
--- a/baselines/showcase/src/v1beta1/echo_client.ts.baseline
+++ b/baselines/showcase/src/v1beta1/echo_client.ts.baseline
@@ -138,6 +138,8 @@ export class EchoClient {
     }
     if (!opts.fallback) {
       clientHeader.push(`grpc/${this._gaxGrpc.grpcVersion}`);
+    } else if (opts.fallback === 'rest' ) {
+      clientHeader.push(`rest/${this._gaxGrpc.grpcVersion}`);
     }
     if (opts.libName && opts.libVersion) {
       clientHeader.push(`${opts.libName}/${opts.libVersion}`);
diff --git a/baselines/showcase/src/v1beta1/identity_client.ts.baseline b/baselines/showcase/src/v1beta1/identity_client.ts.baseline
index 0dc2e7512..fde9f6127 100644
--- a/baselines/showcase/src/v1beta1/identity_client.ts.baseline
+++ b/baselines/showcase/src/v1beta1/identity_client.ts.baseline
@@ -133,6 +133,8 @@ export class IdentityClient {
     }
     if (!opts.fallback) {
       clientHeader.push(`grpc/${this._gaxGrpc.grpcVersion}`);
+    } else if (opts.fallback === 'rest' ) {
+      clientHeader.push(`rest/${this._gaxGrpc.grpcVersion}`);
     }
     if (opts.libName && opts.libVersion) {
       clientHeader.push(`${opts.libName}/${opts.libVersion}`);
diff --git a/baselines/showcase/src/v1beta1/messaging_client.ts.baseline b/baselines/showcase/src/v1beta1/messaging_client.ts.baseline
index 42a3d6113..a065a9e10 100644
--- a/baselines/showcase/src/v1beta1/messaging_client.ts.baseline
+++ b/baselines/showcase/src/v1beta1/messaging_client.ts.baseline
@@ -137,6 +137,8 @@ export class MessagingClient {
     }
     if (!opts.fallback) {
       clientHeader.push(`grpc/${this._gaxGrpc.grpcVersion}`);
+    } else if (opts.fallback === 'rest' ) {
+      clientHeader.push(`rest/${this._gaxGrpc.grpcVersion}`);
     }
     if (opts.libName && opts.libVersion) {
       clientHeader.push(`${opts.libName}/${opts.libVersion}`);
diff --git a/baselines/showcase/src/v1beta1/testing_client.ts.baseline b/baselines/showcase/src/v1beta1/testing_client.ts.baseline
index 9b50f4d95..6bb455c8a 100644
--- a/baselines/showcase/src/v1beta1/testing_client.ts.baseline
+++ b/baselines/showcase/src/v1beta1/testing_client.ts.baseline
@@ -134,6 +134,8 @@ export class TestingClient {
     }
     if (!opts.fallback) {
       clientHeader.push(`grpc/${this._gaxGrpc.grpcVersion}`);
+    } else if (opts.fallback === 'rest' ) {
+      clientHeader.push(`rest/${this._gaxGrpc.grpcVersion}`);
     }
     if (opts.libName && opts.libVersion) {
       clientHeader.push(`${opts.libName}/${opts.libVersion}`);
diff --git a/baselines/tasks/src/v2/cloud_tasks_client.ts.baseline b/baselines/tasks/src/v2/cloud_tasks_client.ts.baseline
index e9d74771f..79d6406e0 100644
--- a/baselines/tasks/src/v2/cloud_tasks_client.ts.baseline
+++ b/baselines/tasks/src/v2/cloud_tasks_client.ts.baseline
@@ -134,6 +134,8 @@ export class CloudTasksClient {
     }
     if (!opts.fallback) {
       clientHeader.push(`grpc/${this._gaxGrpc.grpcVersion}`);
+    } else if (opts.fallback === 'rest' ) {
+      clientHeader.push(`rest/${this._gaxGrpc.grpcVersion}`);
     }
     if (opts.libName && opts.libVersion) {
       clientHeader.push(`${opts.libName}/${opts.libVersion}`);
diff --git a/baselines/texttospeech/src/v1/text_to_speech_client.ts.baseline b/baselines/texttospeech/src/v1/text_to_speech_client.ts.baseline
index 55acf8ca1..cc7ccdd49 100644
--- a/baselines/texttospeech/src/v1/text_to_speech_client.ts.baseline
+++ b/baselines/texttospeech/src/v1/text_to_speech_client.ts.baseline
@@ -130,6 +130,8 @@ export class TextToSpeechClient {
     }
     if (!opts.fallback) {
       clientHeader.push(`grpc/${this._gaxGrpc.grpcVersion}`);
+    } else if (opts.fallback === 'rest' ) {
+      clientHeader.push(`rest/${this._gaxGrpc.grpcVersion}`);
     }
     if (opts.libName && opts.libVersion) {
       clientHeader.push(`${opts.libName}/${opts.libVersion}`);
diff --git a/baselines/translate/src/v3beta1/translation_service_client.ts.baseline b/baselines/translate/src/v3beta1/translation_service_client.ts.baseline
index aada015f9..2b1487035 100644
--- a/baselines/translate/src/v3beta1/translation_service_client.ts.baseline
+++ b/baselines/translate/src/v3beta1/translation_service_client.ts.baseline
@@ -134,6 +134,8 @@ export class TranslationServiceClient {
     }
     if (!opts.fallback) {
       clientHeader.push(`grpc/${this._gaxGrpc.grpcVersion}`);
+    } else if (opts.fallback === 'rest' ) {
+      clientHeader.push(`rest/${this._gaxGrpc.grpcVersion}`);
     }
     if (opts.libName && opts.libVersion) {
       clientHeader.push(`${opts.libName}/${opts.libVersion}`);
diff --git a/baselines/videointelligence/src/v1/video_intelligence_service_client.ts.baseline b/baselines/videointelligence/src/v1/video_intelligence_service_client.ts.baseline
index 2642aad59..102ff5307 100644
--- a/baselines/videointelligence/src/v1/video_intelligence_service_client.ts.baseline
+++ b/baselines/videointelligence/src/v1/video_intelligence_service_client.ts.baseline
@@ -131,6 +131,8 @@ export class VideoIntelligenceServiceClient {
     }
     if (!opts.fallback) {
       clientHeader.push(`grpc/${this._gaxGrpc.grpcVersion}`);
+    } else if (opts.fallback === 'rest' ) {
+      clientHeader.push(`rest/${this._gaxGrpc.grpcVersion}`);
     }
     if (opts.libName && opts.libVersion) {
       clientHeader.push(`${opts.libName}/${opts.libVersion}`);
diff --git a/templates/typescript_gapic/src/$version/$service_client.ts.njk b/templates/typescript_gapic/src/$version/$service_client.ts.njk
index d04c48c1b..9ba37c732 100644
--- a/templates/typescript_gapic/src/$version/$service_client.ts.njk
+++ b/templates/typescript_gapic/src/$version/$service_client.ts.njk
@@ -156,6 +156,8 @@ export class {{ service.name }}Client {
     }
     if (!opts.fallback) {
       clientHeader.push(`grpc/${this._gaxGrpc.grpcVersion}`);
+    } else if (opts.fallback === 'rest' ) {
+      clientHeader.push(`rest/${this._gaxGrpc.grpcVersion}`);
     }
     if (opts.libName && opts.libVersion) {
       clientHeader.push(`${opts.libName}/${opts.libVersion}`);