vipertek double lock steel police edition professional grade handcuffs (black) vipertek sturdy and dependable black double locking steel hand cuffs with welded chain links. the double locking feature allows you to lock the cuffs down to prevent the detainee from closing the cuffs too tight on the wrist. the cuff keys are standard police size and will work on smith and wesson, peerless, and hiatts brands.