Knight Prowler WDL-1012 Roller lifters (Pack of 4) New Full Floating Axle for the lifter roller Race, eliminating flat spots that can lead to failure NEW Load Divider lifter bearing race designed to distribute an even load across the cam lobes, reducing head and stress leading to increased cam and lifter life Newly designed push rod Lifter Cup that insures even, proper oil flow through the push rod to the top end. Newly designed Lifter Body that allows piston jet oil port to remain open with cams up to .750+ Lift.New hydraulic Piston Cup and Check Valve that incease bleed time rate. This corrective action gives you performance like a solid lifter but with an ANTI-PUMP UP hydraulic operation. (NO RETURNS)