Machined from premium-grade hi-tensile chrome silicon single-conical ovate wire Shot-peened with specially processed thermal heat treat and super NexTex? finish for fatigue life needed to exceed high demands of V-Twin engines Use a much smaller and lighter weight retainer to reduce valve weight and create quicker rev and smoother motion Direct bolt-in replacement up to 650″ cam lift; no machining or rocker box clearancing required Kits include: Endurance BeeHive? valve springs, lightweight 7? super Titanium heat-treated retainers, machined spring seats, seat shims, valve locks and a set of premium Viton? valve seals equipped with spring-loaded valve stem wiper system Seat lbs./installed height; 198 lbs. at 1.685″ (.535″ lift), 194 lbs. at 1.703″ (.553″ lift), 190 lbs. at 1.724″ (.574″ lift), 187 lbs. at 1.754″ (.604″ lift), 185 lbs. at 1.780″ (.630″ lift), 160 lbs. at 1.800″ (.650″ lift), 375 lbs. at 1.150″ (open height) coil bind at 1.100″ Feuling? BeeHive? valve springs must be installed at the correct OPEN HEIGHT, matching max lift to the open height spec of the valve springs Made in the U.S.A. Feuling? BeeHive? valve spring kits are direct replacement with no machining or rocker box clearance required up to .574″ lift for 84-04 Big Twin and 86-03 XL and up to .650″ lift for 05-17 Twin Cam. Larger camshafts require valve guide machining for seal to retainer clearance.