These genuine CSP German made push rod tubes are CNC machined from high grade aluminum. To prevent leaking, dual Viton O-rings are utilized and heavy duty stainless steel external springs keep a constant pressure on the end seals even when the engine heats up and expands. 22mm ID on the cylinder head end provide extra clearance for the push rods when high lift rockers are used and 19mm ID on the case end allows for quick oil return top the crankcase. Anodized for a long lasting finish. MADE IN GERMANY.