The trailer coupler lock is made of High quality aluminum alloy and heavy duty steel, the high-quality materials and powder coating finish is durable, rustproof and weatherproof, which makes hitch ball lock last longer.. And it has a striking color, which can effectively prevent the trailer from being stolen. Compare with the traditional keyed design,this type is 4-digit operated combination lock,no need to bring keys and no worry about the missing of the keys anytime and ensure your vehicle safety. Easily installation,the trailer lock with combination lock combines which default combination is “000” with the last anti-theft technology,and it supplied with an instruction manual to tell you how to set your own password, and how to open the lock,when using the fixed correct 4-digit code opened the lock, pushing the locking bar in U-shape comfortably individually in 10 steps over the trailer couplings to get a most suitable place. It is easy and quick to install and remove. Each Trailer Lock set includes 1 Lock unit and 1 instruction manual; This trailer coupler lock can provide the complete security needed when towing or storing a trailer. Included is a universal coupler lock that secures the trailer when not in use; A strong coupler lock, which allows the coupler to be locked when connected to the tow vehicle, It can prevents others from hooking up his vehicle to your trailer can resists picking, prying and drill outs.