CVP Double Pin 5/8" x 1/4" Coupler Lock & Ball Mount Lock One Key System that Opens and Closes Both with One Key; Lock Size: 0.6 x 0.2 inches (15.8 x 6.4 mm), 0.6 inches (15.8 mm), Total Length: 4.2 inches (107 mm), Material: Steel Plating; Special groove key prevents tamper-key from tampering.