diff --git a/bigtable/google/cloud/bigtable/__init__.py b/bigtable/google/cloud/bigtable/__init__.py
index c22cb3fc5379..0c815b8b0988 100644
--- a/bigtable/google/cloud/bigtable/__init__.py
+++ b/bigtable/google/cloud/bigtable/__init__.py
@@ -15,4 +15,7 @@
 """Google Cloud Bigtable API package."""
 
 
+from pkg_resources import get_distribution
+__version__ = get_distribution('google-cloud-bigtable').version
+
 from google.cloud.bigtable.client import Client
diff --git a/bigtable/google/cloud/bigtable/client.py b/bigtable/google/cloud/bigtable/client.py
index 06b35c6d9e94..2f552b1c2564 100644
--- a/bigtable/google/cloud/bigtable/client.py
+++ b/bigtable/google/cloud/bigtable/client.py
@@ -32,21 +32,24 @@
 import os
 
 import google.auth.credentials
+from google.gax.utils import metrics
 from google.longrunning import operations_grpc
 
 from google.cloud._helpers import make_insecure_stub
 from google.cloud._helpers import make_secure_stub
+from google.cloud._http import DEFAULT_USER_AGENT
+from google.cloud.client import _ClientFactoryMixin
+from google.cloud.client import _ClientProjectMixin
+from google.cloud.credentials import get_credentials
+from google.cloud.environment_vars import BIGTABLE_EMULATOR
+
+from google.cloud.bigtable import __version__
 from google.cloud.bigtable._generated import bigtable_instance_admin_pb2
 from google.cloud.bigtable._generated import bigtable_pb2
 from google.cloud.bigtable._generated import bigtable_table_admin_pb2
 from google.cloud.bigtable.cluster import DEFAULT_SERVE_NODES
 from google.cloud.bigtable.instance import Instance
 from google.cloud.bigtable.instance import _EXISTING_INSTANCE_LOCATION_ID
-from google.cloud.client import _ClientFactoryMixin
-from google.cloud.client import _ClientProjectMixin
-from google.cloud._http import DEFAULT_USER_AGENT
-from google.cloud.credentials import get_credentials
-from google.cloud.environment_vars import BIGTABLE_EMULATOR
 
 
 TABLE_ADMIN_HOST = 'bigtableadmin.googleapis.com'
@@ -67,10 +70,17 @@
 READ_ONLY_SCOPE = 'https://www.googleapis.com/auth/bigtable.data.readonly'
 """Scope for reading table data."""
 
+_METRICS_HEADERS = (
+    ('gccl', __version__),
+)
+_HEADER_STR = metrics.stringify(metrics.fill(_METRICS_HEADERS))
+_GRPC_EXTRA_OPTIONS = (
+    ('x-goog-api-client', _HEADER_STR),
+)
 # NOTE: 'grpc.max_message_length' will no longer be recognized in
 #       grpcio 1.1 and later.
 _MAX_MSG_LENGTH_100MB = 100 * 1024 * 1024
-_GRPC_MAX_LENGTH_OPTIONS = (
+_GRPC_MAX_LENGTH_OPTIONS = _GRPC_EXTRA_OPTIONS + (
     ('grpc.max_message_length', _MAX_MSG_LENGTH_100MB),
     ('grpc.max_receive_message_length', _MAX_MSG_LENGTH_100MB),
 )
@@ -107,7 +117,7 @@ def _make_instance_stub(client):
         return make_secure_stub(
             client.credentials, client.user_agent,
             bigtable_instance_admin_pb2.BigtableInstanceAdminStub,
-            INSTANCE_ADMIN_HOST)
+            INSTANCE_ADMIN_HOST, extra_options=_GRPC_EXTRA_OPTIONS)
     else:
         return make_insecure_stub(
             bigtable_instance_admin_pb2.BigtableInstanceAdminStub,
@@ -127,9 +137,10 @@ def _make_operations_stub(client):
     :returns: A gRPC stub object.
     """
     if client.emulator_host is None:
-        return make_secure_stub(client.credentials, client.user_agent,
-                                operations_grpc.OperationsStub,
-                                OPERATIONS_API_HOST)
+        return make_secure_stub(
+            client.credentials, client.user_agent,
+            operations_grpc.OperationsStub,
+            OPERATIONS_API_HOST, extra_options=_GRPC_EXTRA_OPTIONS)
     else:
         return make_insecure_stub(operations_grpc.OperationsStub,
                                   client.emulator_host)
@@ -148,7 +159,7 @@ def _make_table_stub(client):
         return make_secure_stub(
             client.credentials, client.user_agent,
             bigtable_table_admin_pb2.BigtableTableAdminStub,
-            TABLE_ADMIN_HOST)
+            TABLE_ADMIN_HOST, extra_options=_GRPC_EXTRA_OPTIONS)
     else:
         return make_insecure_stub(
             bigtable_table_admin_pb2.BigtableTableAdminStub,
diff --git a/bigtable/setup.py b/bigtable/setup.py
index 06db1ac10ce1..25e12f76b011 100644
--- a/bigtable/setup.py
+++ b/bigtable/setup.py
@@ -51,7 +51,7 @@
 
 REQUIREMENTS = [
     'google-cloud-core >= 0.23.1, < 0.24dev',
-    'grpcio >= 1.0.2, < 2.0dev',
+    'google-gax>=0.15.7, <0.16dev',
 ]
 
 setup(
diff --git a/bigtable/unit_tests/test_client.py b/bigtable/unit_tests/test_client.py
index b7b666e819df..8761dc360c81 100644
--- a/bigtable/unit_tests/test_client.py
+++ b/bigtable/unit_tests/test_client.py
@@ -36,39 +36,24 @@ def _call_fut(self, client):
 
         return _make_data_stub(client)
 
-    def test_without_emulator(self):
-        from google.cloud._testing import _Monkey
+    @mock.patch('google.cloud.bigtable.client.make_secure_stub',
+                return_value=mock.sentinel.stub)
+    def test_without_emulator(self, make_stub):
         from google.cloud.bigtable import client as MUT
 
         credentials = _make_credentials()
         user_agent = 'you-sir-age-int'
         client = _Client(credentials, user_agent)
 
-        fake_stub = object()
-        make_secure_stub_args = []
-
-        def mock_make_secure_stub(*args, **kwargs):
-            make_secure_stub_args.append(args)
-            make_secure_stub_args.append(kwargs)
-            return fake_stub
-
-        with _Monkey(MUT, make_secure_stub=mock_make_secure_stub):
-            result = self._call_fut(client)
-
-        extra_options = {'extra_options': (
-            ('grpc.max_message_length', 104857600),
-            ('grpc.max_receive_message_length', 104857600)
-        )}
-        self.assertIs(result, fake_stub)
-        self.assertEqual(make_secure_stub_args, [
-            (
-                client.credentials,
-                client.user_agent,
-                MUT.bigtable_pb2.BigtableStub,
-                MUT.DATA_API_HOST,
-            ),
-            extra_options,
-        ])
+        result = self._call_fut(client)
+        self.assertIs(result, mock.sentinel.stub)
+        make_stub.assert_called_once_with(
+            client.credentials,
+            client.user_agent,
+            MUT.bigtable_pb2.BigtableStub,
+            MUT.DATA_API_HOST,
+            extra_options=MUT._GRPC_MAX_LENGTH_OPTIONS,
+        )
 
     def test_with_emulator(self):
         from google.cloud._testing import _Monkey
@@ -103,33 +88,24 @@ def _call_fut(self, client):
 
         return _make_instance_stub(client)
 
-    def test_without_emulator(self):
-        from google.cloud._testing import _Monkey
+    @mock.patch('google.cloud.bigtable.client.make_secure_stub',
+                return_value=mock.sentinel.stub)
+    def test_without_emulator(self, make_stub):
         from google.cloud.bigtable import client as MUT
 
         credentials = _make_credentials()
         user_agent = 'you-sir-age-int'
         client = _Client(credentials, user_agent)
 
-        fake_stub = object()
-        make_secure_stub_args = []
-
-        def mock_make_secure_stub(*args):
-            make_secure_stub_args.append(args)
-            return fake_stub
-
-        with _Monkey(MUT, make_secure_stub=mock_make_secure_stub):
-            result = self._call_fut(client)
-
-        self.assertIs(result, fake_stub)
-        self.assertEqual(make_secure_stub_args, [
-            (
-                client.credentials,
-                client.user_agent,
-                MUT.bigtable_instance_admin_pb2.BigtableInstanceAdminStub,
-                MUT.INSTANCE_ADMIN_HOST,
-            ),
-        ])
+        result = self._call_fut(client)
+        self.assertIs(result, mock.sentinel.stub)
+        make_stub.assert_called_once_with(
+            client.credentials,
+            client.user_agent,
+            MUT.bigtable_instance_admin_pb2.BigtableInstanceAdminStub,
+            MUT.INSTANCE_ADMIN_HOST,
+            extra_options=MUT._GRPC_EXTRA_OPTIONS,
+        )
 
     def test_with_emulator(self):
         from google.cloud._testing import _Monkey
@@ -164,35 +140,25 @@ def _call_fut(self, client):
 
         return _make_operations_stub(client)
 
-    def test_without_emulator(self):
+    @mock.patch('google.cloud.bigtable.client.make_secure_stub',
+                return_value=mock.sentinel.stub)
+    def test_without_emulator(self, make_stub):
         from google.longrunning import operations_grpc
-
-        from google.cloud._testing import _Monkey
         from google.cloud.bigtable import client as MUT
 
         credentials = _make_credentials()
         user_agent = 'you-sir-age-int'
         client = _Client(credentials, user_agent)
 
-        fake_stub = object()
-        make_secure_stub_args = []
-
-        def mock_make_secure_stub(*args):
-            make_secure_stub_args.append(args)
-            return fake_stub
-
-        with _Monkey(MUT, make_secure_stub=mock_make_secure_stub):
-            result = self._call_fut(client)
-
-        self.assertIs(result, fake_stub)
-        self.assertEqual(make_secure_stub_args, [
-            (
-                client.credentials,
-                client.user_agent,
-                operations_grpc.OperationsStub,
-                MUT.OPERATIONS_API_HOST,
-            ),
-        ])
+        result = self._call_fut(client)
+        self.assertIs(result, mock.sentinel.stub)
+        make_stub.assert_called_once_with(
+            client.credentials,
+            client.user_agent,
+            operations_grpc.OperationsStub,
+            MUT.OPERATIONS_API_HOST,
+            extra_options=MUT._GRPC_EXTRA_OPTIONS,
+        )
 
     def test_with_emulator(self):
         from google.longrunning import operations_grpc
@@ -229,33 +195,24 @@ def _call_fut(self, client):
 
         return _make_table_stub(client)
 
-    def test_without_emulator(self):
-        from google.cloud._testing import _Monkey
+    @mock.patch('google.cloud.bigtable.client.make_secure_stub',
+                return_value=mock.sentinel.stub)
+    def test_without_emulator(self, make_stub):
         from google.cloud.bigtable import client as MUT
 
         credentials = _make_credentials()
         user_agent = 'you-sir-age-int'
         client = _Client(credentials, user_agent)
 
-        fake_stub = object()
-        make_secure_stub_args = []
-
-        def mock_make_secure_stub(*args):
-            make_secure_stub_args.append(args)
-            return fake_stub
-
-        with _Monkey(MUT, make_secure_stub=mock_make_secure_stub):
-            result = self._call_fut(client)
-
-        self.assertIs(result, fake_stub)
-        self.assertEqual(make_secure_stub_args, [
-            (
-                client.credentials,
-                client.user_agent,
-                MUT.bigtable_table_admin_pb2.BigtableTableAdminStub,
-                MUT.TABLE_ADMIN_HOST,
-            ),
-        ])
+        result = self._call_fut(client)
+        self.assertIs(result, mock.sentinel.stub)
+        make_stub.assert_called_once_with(
+            client.credentials,
+            client.user_agent,
+            MUT.bigtable_table_admin_pb2.BigtableTableAdminStub,
+            MUT.TABLE_ADMIN_HOST,
+            extra_options=MUT._GRPC_EXTRA_OPTIONS,
+        )
 
     def test_with_emulator(self):
         from google.cloud._testing import _Monkey