2 Pack, 5/8", 16 mm, Class III/IV, Barbell Pin Receiver Lock, Keyed Alike, Includes The Push To Lock Locking Mechanism, Easily Used By Pushing The Lock Body Firmly Onto The Pin & Removing The Key, Weather Tough Seal & Water Tight Cap Provides Additional Protection From Moisture & Dirt, Fits 5/8", 16mm Receivers, Usable Length Of Receiver Pin Is 2-3/4", 70 mm, 10,000 LB Load Rating, 4 Pin Cylinder For Added Pick Resistance, Uses Master Lock Key Blank K1BOX Or Ilco Blank M1 TV #320-952, Not Included.