Rivera Primo Brute III Extreme 11mm 1-3/4in. Enlosed Belt Drive System - 106-Tooth Ring Gear 2015-0066 Specifically designed for extreme shockloads generated by large displacement, highly modified American V-Twins Includes Primos Pro Clutch Assembly 11mm 1-3/4in. Kevlar polychain belt is extremely durable 150+ HP capability Low maintenance