The S&S Breather Reed Valve for 2003-up Harley-Davidson® big twins consists of a machined billet aluminum body which contains four steel reed valves. The valve body slides over the pinion shaft and inside the pinion bearing bore. It is contained between the pinion bearing and the oil pump. The reed valves allow air and oil mist to escape from the crankcase, but do not allow them to re-enter. Fits 2003 - up Harley-Davidson® Twin Cam 88® and Twin Cam 96™ engines with stock or S&S Super Stock crankcases