UL1 Ultimate Hinge Cuff is made with heavy-duty construction and oversized rivet heads for added strength. The18 teeth - 3 retaining bars with 6 teeth on each bar makes cuffs extremely difficult to pick and a built-in backloading feature for faster cuffing. The leaf spring double locking system is very difficult to defeat and True Swing Technology ensures the shackle hits the center of the cuff every time. The Ultimate Hinge Cuff snaps open to a flat profile, then locks into position, becoming rigid for use and folds for easy storage. They lock and double lock like regular handcuffs using a standard handcuff key.