3/16 welded steel construction with a no-nonsense design which fully encompasses the ball heads of the various couplers shown to include the Atwood, the HD Bulldog adjustable and the standard U-Haul coupler. Accepts most "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 (sold separately) with varying levels of security. DO call us for clarification if you have any questions. Be sure to check out our installation video HERE. We offer discounts starting at 10 or more Ft. Knox Locks. If your coupler is not represented in the photos for this Ft. Knox Lock it will not work. Bright yellow powder coat. Made in America!