A lock for the hook of a roll-off container box comprises a rail member with two substantially parallel brackets, each bracket having a plurality of apertures for receiving at least one padlock, said brackets terminating at one end in a carrying handle and at the opposite end with a connector pin for engaging with the container box hook. The lock further comprises a box-like outer cover for the rail member, that outer cover having a front wall, a rear wall, a top surface and spaced apart sidewalls. Each sidewall has a track that commences at its bottom edge, and extends parallel to that bottom edge before branching off into an upper and lower pathway for the rail member's connector pin to slide along.