Top-quality piston kit featuring superior ring seal, bore compatibility, quiet running and longer lifespan 2,000 hours of durability testing behind every piston Auto-Fit Coating is a permanently bonded, moly-based coating process, designed to last for the life of the piston Accurate to a 30-micron thickness to deliver tight piston-to-sidewall clearances for ultra-quiet operation Gas nitride-coated rings offer the ultimate compatibility with nickel-silicon-carbide-plated bores Replacement piston rings are available separately (sold as a set for one piston); NOTE: Piston kits are intended for use with Revolution Big Bore Kits only; NOTE: Not recommended for use with cast iron cylinders