The Redi-Edge Challenge Coin Knife Sharpener is unmatched in its design and effectiveness. The convenient "challenge coin" design enhances the portability of the sharpener. The Marine Corp version of the Redi-Edge Challenge Coin is engraved with the USMC logo on the front and the Eagle, Globe and Anchor on the back. Klawhorn Industries, Inc., manufacturer of the Redi-Edge Challenge Coin, is an official trademark licensee of the United States Marine Corp.