Smith & Wesson Model 100-1 Handcuffs are constructed of nickel plated carbon steel. Carbon steel provides strength and nickel plating creates a corrosion resistant surface. The satin nickel finish is not shiny and makes the handcuffs appear cloudy. They do this to ensure the handcuffs are both non-reflective and easy to grip. These handcuffs use the slot lock double locking mechanism, to double lock these handcuffs insert the double lock pin on your handcuff key into the double lock slot and pull down towards the keyhole. Double locking handcuffs makes them harder to shim, it also prevents the handcuffs from being further tightened. When double locked, handcuffs cannot be tightened or picked. Includes two handcuff keys, Smith & Wesson's lifetime warranty and instructions.