The vendor part number is 4055. Read title careful to know what you are getting. Full travel hydraulic lifters are machined from a steel body and designed to exceed the needs of large lift camshafts and higher valve spring pressures with a slower bleed down rate. Lifters maintain proper oil flow to the top end, increase engine RPM, valve-train stability, decreasing valve float promoting maximum valve lift. Lifters for engines running higher than 185Lbs. FEULING recommends the use of a high volume oil pump which will result in quieter, better performing lifters. Lifters are compatible with either FEULING. Oil pumps and are designed for use with both street and strip engines. Spin-Tron dyno developed and track proven, Made in the USA. Available in oversized diameters – Case Savers! Recommended for both strip and performance street engines. Made in the U.