Ultra-High Security Coupler/Hitch Trailer Lock: This strong and straightforward trailer coupler/hitch lock is designed to secure the Bulldog sliding collar coupler. Heavy Duty/Ultra-High Security: This no-nonsense coupler lock is constructed of 3/16" fully welded cold rolled steel, with welded hinges and hinge pins and is bolt cutterand crowbar proof! High Security Puck Lock: Cobra SideWinder have extreme picking resistance, limited key blank access and over 250 million key code combinations available. Each Cobra SideWinder lock has 10+ combination locking plates each containing multiple anti picking grooves. The locking plates align with a sidebar to keep the inner cylinder engaged with the shell in the locked position. SideWinder locks have a Symmetrical key that will work in either direction, making this a very user-friendly lock. Bright Yellow Powder Coat Finish: We believe in presenting a hard target that is why we use a bright yellow powder coat to warn off would be thieves. Double Check Your Coupler/Hitch: This lock only fits the coupler/hitchs Bulldog sliding collar pictured. If you do not see your coupler/hitch, please view our other coupler/hitch locks. Ft. Knox Locks: We are a family run and operated small business with our locks designed and proudly made in the USA.