- Jaw Jacker Modern Combative Systems is proud to announce the Jaw Jacker polymer knuckleduster, a collaboration between George Matheis (Mercop) and Jeff Ferrand at Alpha Innovations. This is a novelty item that is not intended for carry or use. Although it is incredibly strong (it is made of the same reinforced polymer as our other products) the idea behind it is to show what our idea of an ideal knuckle would look like. Disclaimer It is the buyers responsibility to know and abide by your local laws, regulations and ordinances governing the ownership of such an item in your country, province, state or county. We, as the seller, assume no risk. Must be at least 18 to purchase. This product is for novelty use only and is not intended to be used in a harmful manner. Improper use of this item could inflict harm to other human beings, animals or personal property. If you use this product for other than our stated purpose you will be held responsible and will hold us harmless from any liability. We make no warranty in regards to improper use of this product. Buyer confirms and agrees to all terms and conditions of this disclaimer upon purchase of item. The Jaw Jacker measures about 1/2" thick x 4 3/4" wide x 2 5/8" long. It has 1" diameter finger holes.