Trimax Stainless Steel Receiver/Coupler Lock Set. The SXT3 Receiver Lock fits a 5/8" x 2-3/4" span. The SXTC1 Coupler Lock fits a 7/8" span. Both locks are keyed alike. One key operates both locks. The O-ring seal and water tight cap help seal out dirt. Easy 1/4 turn locks and unlocks head. Features of Trimax SXTM31 Stainless Steel Receiver/Coupler Lock Set Keyed-alike locks Fits 5/8" Class III Receivers Coupler lock fits a 7/8" span Includes one SXT3 Stainless Steel Key Receiver Lock one SXTC1 Stainless Steel Coupler Lock and four round keys The round key won't bend or break like flat keys and are impossible to pick. Package Contents: Trimax SXTM31 Stainless Steel Receiver/Coupler Lock Set Trimax SXTM31: Stainless Steel Receiver/Coupler Lock Set