The TowSmart ProClass Heavy Duty Coupler Lock protects your boats, campers, trailers, and equipment from theft. The coupler lock provides multiple locking positions. It features a 9/16 In. heavy gauge locking bar and fine-tooth adjustment, and a round key locking cylinder for greater security and theft deterrence. Simply slide the ball into the coupler, connect the heavy duty shackle, and use the included key to lock into place. Easy to install, provides a tight and secure fit, and is made of corrosion-resistant materials designed to withstand extreme weather. The bright finish is highly visible to prevent others from tampering with your trailer.