Polished 316 stainless steel high security key locks with anti-drill protection secure outboard to your boat. The Bar Lock is great for small outboards, does not rattle and is extremely secure. For permanently mounted larger outboards the Bolt Locks backing plate installs under engine transom nut and fits up to 1/2" engine bolts. Noise dampeners reduce rattle. Each lock includes two keys, which cannot be duplicated without 5 digit key card (also included).