Easy operation — 1/4 turn locks & unlocks head. Can’t pop open or be falsely locked. Exclusive design incorporates O-Rings and water tight cap to help seal out dirt and corrosion in the lock head mechanism. Full length solid forged lock pin can’t pull out.Fits Class III trailer receivers (2" x 2").Machined Hardened Steel TM31 Set contains: TC1 (1/2"-7/8" span) coupler lock and a T3: 5/8" x 2-3/4" rodTM32 Set contains: TC2 (2-1/2" span) and a T3: 5/8" x 2-3/4" rodStainless SteelSXTM31 Set contains:TC1 (1/2"-7/8" span) and a T3: 5/8" x 2-3/4" rod.SXTM32 Set contains:TC2 (2-1/2" span) and a T3: 5/8" x 2-3/4" rod.