The Dirt Tricks Front Sprocket is built from an ultra-hard tool steel. Most front sprockets sold today are “case hardened”, meaning that only a thin outer layer of steel is hardened. Below that layer is soft steel. Dirt Tricks front sprockets are heat treated, giving them the ultimate toughness and wear resistance. How it is such a hard material without it being brittle? Shock resistant tool steel is the answer. This is the same steel used to punch holes through 1″ thick plates of steel, on high speed punch presses.