diff --git a/samples/manager/manager.js b/samples/manager/manager.js
index 06ee202a..2b956390 100644
--- a/samples/manager/manager.js
+++ b/samples/manager/manager.js
@@ -449,7 +449,34 @@ const listDevices = async (registryId, projectId, cloudRegion) => {
       registryId
     );
 
-    const [response] = await iotClient.listDevices({parent: parentName});
+    // See full list of device fields: https://cloud.google.com/iot/docs/reference/cloudiot/rest/v1/projects.locations.registries.devices
+    // Warning! Use snake_case field names.
+    const fieldMask = {
+      paths: [
+        'id',
+        'name',
+        'num_id',
+        'credentials',
+        'last_heartbeat_time',
+        'last_event_time',
+        'last_state_time',
+        'last_config_ack_time',
+        'last_config_send_time',
+        'blocked',
+        'last_error_time',
+        'last_error_status',
+        'config',
+        'state',
+        'log_level',
+        'metadata',
+        'gateway_config',
+      ],
+    };
+
+    const [response] = await iotClient.listDevices({
+      parent: parentName,
+      fieldMask,
+    });
     const devices = response;
 
     if (devices.length > 0) {
@@ -620,7 +647,34 @@ const getDevice = async (deviceId, registryId, projectId, cloudRegion) => {
       deviceId
     );
 
-    const [response] = await iotClient.getDevice({name: devicePath});
+    // See full list of device fields: https://cloud.google.com/iot/docs/reference/cloudiot/rest/v1/projects.locations.registries.devices
+    // Warning! Use snake_case field names.
+    const fieldMask = {
+      paths: [
+        'id',
+        'name',
+        'num_id',
+        'credentials',
+        'last_heartbeat_time',
+        'last_event_time',
+        'last_state_time',
+        'last_config_ack_time',
+        'last_config_send_time',
+        'blocked',
+        'last_error_time',
+        'last_error_status',
+        'config',
+        'state',
+        'log_level',
+        'metadata',
+        'gateway_config',
+      ],
+    };
+
+    const [response] = await iotClient.getDevice({
+      name: devicePath,
+      fieldMask,
+    });
     const data = response;
 
     console.log('Found device:', deviceId, data);