Master Lock Trailer Lock, Universal Trailer Coupler Lock, 379DAT LOCK APPLICATION: Best used for vehicles, trailers, and RV hitch locks EASE OF USE: Trailer hitch lock is easy to install and remove DURABLE DESIGN: Trailer coupler resists rust and corrosion; Advanced locking mechanism resists picking and prying SPECIFICATIONS: Fits 1-7/8 in., 2 in. and most 2-5/16 in. couplers INCLUDES: One coupler lock, two keys