Trailer hitch lock fits 1-7/8 in. (48mm), 2 in. (51mm) and most 2-5/16 in. (59mm) trailer couplers Trailer lock is best used for vehicles, trailers, and RVs Trailer coupler lock features advanced locking mechanism to resist picking and prying Trailer hitch lock is constructed from zinc to resist rust and corrosion Includes one trailer coupler lock, two keys