Cole Hersee patent. Keeps plugs clean when not in use and extends life by protecting electrical contacts from dirt and roadsplash. For all SAE J560b 7-pole plugs and 13-pole plugs. Spring-loaded for secure locking. Heavy duty glass-filled plastic housing. Fits 11100-02, 12311, 1222, 1255, 12091, 12092, 12081, 12082, 12301 and 11042-05.