Model 300 Hinged HandcuffsMore Restrictive than Standard Chain Handcuffs Slot Lock Double Locking Mechanism Two Keys Included Available in Nickel or Blue Finish The Smith & Wesson's model 300 hinged police handcuffs are more restrictive than standard chain handcuffs. The model 300 is constructed of carbon steel and is nickel plated. Satin nickel plating provides corrosion resistance and makes the handcuffs appear dull or cloudy to prevent glare in tactical situations where