metal caribiner clips work well too. Thing with raccoons is, you need double protection. The little buggers are smart. If they get the hook off, (which is possible if the raccoon has worked them before) they still have to turn the center of the hasp. Hopefully, either the hook or hasp are stiff enough that he can't move them. I play it save and put locks on everything. I haven't met a raccoon that can use a key.