3/16 welded steel construction with a no-nonsense design which fully encompasses the ball receiver head of a Bulldog sliding collar coupler.  Fits both the 2″ & 2 5/16″ ball size.  Accepts most all “puck” style locks (sold separately) which by design are completely bolt cutter proof. Time, noise, power tools or a cutting torch will be required to defeat our lock design which will eliminate most theft interest. We also sell a few different brands of the “puck” style locks with varying levels of security. DO call us for clarification if you have any questions. Be sure to check out the installation video HERE. We offer discounts starting at 10 or more Ft. Knox Locks. There is a VERY similar coupler that is commonly called a Bulldog but is in fact a “RAM” brand coupler.  We also have the lock for that coupler and you should compare our pictures of the Bulldog and the RAM locks to ensure proper fit as they are slightly different. Made in America!