Trimax Receiver/Coupler Lock Set. Convenient 1/4 turn locks and unlocks head. Rugged lock can't pop open or be false locked. Exclusive O-Ring and Dust Cap helps seal out dirt and water. T3 Receiver lock - 5/8 in. PIN fits Class III 2 in. x 2 in. receivers - TC3 coupler lock - Fits Surge brake couplers with up to 3-1/2 in. span. Includes four matching keys. Features of Trimax Receiver/Coupler Lock Set Complete security-same key locks receiver and coupler Convenient 1/4 turn locks and unlocks head Rugged lock can't pop open or be false locked Exclusive O-Ring and Dust Cap helps seal out dirt and water T3 Receiver lock - 5/8 in. PIN fits Class III 2 in. x 2 in. receivers - TC3 coupler lock - Fits Surge brake couplers with up to 3-1/2 in. span Package Contents: Trimax Receiver/Coupler Lock Set Trimax TM31: TM31 Receiver/Coupler Lock Set