99-18 YAMAHA YZF-R6: Driven Racing Front Sprocket (520/16 Tooth) Every Driven Sprocket is manufactured to a rigorous standard of quality which is unsurpassed in the industry. Designed using Driven Racing's proprietary EST Technology. Driven steel sprockets are manufactured using only the highest quality 45C steel available. Steel sprockets are heat treated and then quenched for maximum strength and durability. Every sprocket is guaranteed against defects in materials and workmanship; performance and reliability in one sprocket.