I had a locking cap on for years. It didnt need the key to get it off. Just move to one side and pull and it would come off but it looked locked when it was on. Then one day it wouldn't come off no matter what. Of course the keys were gone long ago because i never needed them. Nearly had to damage the filler opening to get the [censored] thing off. Got a regular cap now. S&W is the best gas lock made. #2 would be trunk monkey( youtube it if you haven't seen it).