Vertex Top End Kit 4T KX450F 21-23 Compr. 13.5:1 (95.96) Vertex top-end kits include; piston, rings, circlips, piston pin, base gaskets, head o-rings and piston pin bearing. All pistons are heat treated with T-5 hardening and a tempering cycle New T-box forgings and DLC coated wrist pins on forged pistons with highest compression ratios for increased strength and performance. Piston skirts are coated with a hi-tech molybdenum disulphide for faster break-in time Nitride coating for increased piston life Top end piston kit includes: piston, rings, pins, circlips, base gaskets, head o-rings and wrist pin bearing when applicable. Kits are exact O.E.M. replacements Replica KTM 2-stroke pistons are factory supplied to KTM Two-stroke piston kits made from gravity cast aluminum alloy with 18% silicone content, which produces an extremely light but very strong piston