Designed to work on custom shorter engines (shorter cylinders/decked heads; thinner head gaskets) and using stock style full travel lifters. -0.040" shorter than stock. Fixed Length one-piece; which makes them stronger than adjustable pushrods. Made of 4130 chrome moly with swedged formed ends. Heavy duty 7/16 diameter tube with 0.165" wall thickness; precision concentricity; heat treated with a black oxide finish. Designed to eliminate pushrod flex; reduce valve-train harmonics and increase valve lift. Quick install pushrods are easier to use; however they cannot compare to a solid pushrod for strength and durability. Note: Since these pushrods fixed lengths they cannot be adjusted for other cams / engine set-ups than what they are designed for.