Auto-Fit Coating a patent pending permanently bonded, moly-based coating process designed to last for the life of the piston Applied to 30 micron thickness allowing for tight piston to sidewall clearances for ultra quiet operation Gas nitride coated rings for ultimate compatibility with NSC plated bores Over 2000 hours of durability testing to insure the quality of the pistons 3.563" bore, 4.25" stroke,10.5:1 comp