Amazon.com: CZC AUTO Locking Hitch Pin Fit 2" & 2.5" Receiver, Trailer Hitch Lock with 5/8" Pin, Hitch Pin Lock for Class III IV, Chrome Coated Tow Hitch Locking Pin with Keys :
Amazon.com: CZC AUTO Hitch Lock Set, Dia 5/8 Inch Trailer Hitch Lock Hitch Receiver Pin Lock for Class III IV 2" and 2-1/2" Receiver, Dia 1/4 Inch Hitch Coupler Lock with 3/4
Speedrite Double Nail Pin-Lock -Black Insulator Pack of 25