STRONG. TOUGH. SIMPLE. The DeadBolt / CT Johnson Blockhead Trailer Coupler Lock is designed with high-tech materials that redefine the traditional lip engaging coupler lock. The heavy-wall cast aircraft aluminum body provides superior strength-to-weight ratio, a distinctive look, and great value.• Simple, quarter turn lock mechanism• Fits flat lip style 2-5/16" couplers• Durable, exterior-grade powder-coat finish• Double-sided automotive style key for easy insertion and removalNOTE: Fits 2-5/16" lip-engaging, trigger-style couplers. Coupler should have flat lip around the bottom. Maximum lip width: 4-1/2". Simple quarter-turn lock mechanism Double-sided automotive style key for easy insertion & removal Fits flat lip style 2-5/16"" couplers | C.T. Johnson DeadBolt / CT Johnson Blockhead Trailer Coupler Lock, 2-5/16"