The Lock-Top II comes fully assembled. Its base mounts to the included sweep's ring which attaches to the flue tile with silicone sealant (included). A 30' stainless steel cable and hardware are also included. All Lock-Top II cap/dampers have an overall height of 11-3/8".
Note: Don't use Lock-Top dampers with gas logs - failure to open could cause carbon monoxide to back up into the house. In case of a gas leak, gas could be trapped in the flue, resulting in an explosion.