Rear Sprocket. JT Steel Sprockets are manufactured using the latest generation of computer design and control metal cutting equipment and only the finest grade of C49 high carbon steel. The JT Steel Sprockets range now contains over 2,500 parts for all motorcycles and ATVs. Made exclusively from the finest high carbon steel. Outlasts any mild steel or surface hardened sprocket. Heat treated and hand finished to meet or exceed the highest possible quality standards. Black version uses an induction-hardened black zinc finish.