Rollmaster Timing Chain Sets utilize billet steel construction for the upper and lower sprockets rather than cast iron. This reduces wear and improves accuracy by providing 100% CNC machined Surfaces. For easy timing adjustments, most sets include a nine keyway positions on the lower sprocket. This eliminates the need for offset bushings and provides a more reliable and consistent adjustment than adjustable eccentric style pins or multi part upper sprockets. All Rollmaster Timing Chain sets include an exclusive IWIS Timing Chain, widely recognized at the best timing chain available worldwide.