Solid flat bar steel manufactured coupling locks with zinc plating corrosion protection. The large model locks around the trailer coupling and towing vehicle tow ball, preventing disconnection but still allowing full trailer articulation, this is achieved with the clamp bar in the top position as pictured. The large clamp (with lock bar in lower position) and the small clamp, lock around the trailer coupling when trailer is not connected, preventing attachment to a vehicle. The padlocks on the relevant models are solid brass with 8mm stainless steel shank.