The Smith & Wesson model 300B is the black version of their model 300 hinged handcuff. Hinged handcuffs are more restrictive than standard chain handcuffs. The model 300B is constructed of carbon steel and is blued using traditional bluing methods to create a black non-reflective finish for patrol & tactical applications. The hinged design safely restricts movement providing more security for officers. Smith & Wesson’s model 300B is a double locking black handcuff that utilizes the slot lock double locking mechanism. Simply insert the back of your handcuff key into the slot and pull towards the keyhole to double lock these handcuffs. These handcuffs can be double locked from both sides. The 300B comes with 2 Smith & Wesson handcuff keys, instructions and a lifetime warranty.