koga sd1 made of high impact polymer - good for self defense, security and sports. cold steel the cold steel koga sd series are made of a high-impact polymer, and are designed to function as an aid in leverage when restraining an individual, and obtaining joint locks or submission holds. but they also serve as an admirable “intermediate impact tool”.<br><br> weight 4.1 oz.<br> overall 7 1/2" <br><br>