Towball lock with zinc alloy casing. Fixes into coupling head to prevent unauthorised use. Suitable for most 50mm ball couplings. Easy to install. Includes 2 x nickel-plated brass keys and 6mm hex adjustment key. Weight: 0.34kg. Towball lock with zinc alloy casing. Fixes into coupling head to prevent unauthorised use. Suitable for most 50mm ball couplings. Easy to install. Includes 2 x nickel-plated brass keys and 6mm hex adjustment key. Weight: 0.34kg.