diff --git a/xos/synchronizer/models/volt.xproto b/xos/synchronizer/models/volt.xproto
index aa2518d..380c835 100644
--- a/xos/synchronizer/models/volt.xproto
+++ b/xos/synchronizer/models/volt.xproto
@@ -29,9 +29,9 @@
 
     required manytoone volt_service->VOLTService:volt_devices = 1 [db_index = True, null = False, blank = False];
     required string name = 2 [help_text = "name of device", max_length = 254, null = False, db_index = False, blank = False];
-    required string device_type = 3 [help_text = "Device Type", default = "asfvolt16_olt", max_length = 254, null = False, db_index = False, blank = False];
-    required string host = 4 [help_text = "Host", max_length = 254, null = False, db_index = False, blank = False];
-    required int32 port = 5 [help_text = "Fabric port", null = False, db_index = False, blank = False];
+    required string device_type = 3 [help_text = "Device Type", default = "asfvolt16_olt", max_length = 254, null = False, db_index = False, blank = False, tosca_key=True];
+    required string host = 4 [help_text = "Host", max_length = 254, null = False, db_index = False, blank = False, tosca_key=True];
+    required int32 port = 5 [help_text = "Fabric port", null = False, db_index = False, blank = False, tosca_key=True];
 
     optional string device_id = 10 [help_text = "Device ID", null = True, db_index = False, blank = False, feedback_state = True];
     optional string admin_state = 11 [help_text = "admin_state", null = True, db_index = False, blank = False, feedback_state = True];