S&S Cycle Premium High-Performance Hydraulic Tappets Big Twin with HL2T Reduced valve train noise from start up to shut down Close tolerances for low leak down rates - fast pump up and superior high rpm performance Low mass, bearing grade, silicon nitride check ball and lighter check ball spring-enhances fast pump up and quiet operation 100% tested to ensure that leak down and top end oil flow are within specification HL2T is a limited travel spacer that is great for higher RPMs, stronger valve springs and more aggressive cam profiles