Manley pistons are machined of high strength 2618 material. Each design is lightweight yet robust enough to deliver long service life. Offset wrist pin design is utilized for quiet start-ups. Perfect ring groove to skirt squareness is achieved through our unique "one fixturing" manufacturing method that assures maximum horsepower. All pistons come with moly coated skirts and will accommodate +1mm valve sizes. Round wire locks, premium chrome moly wrist pins (P/N 42251), premium steel top ring, Napier style second ring and higher tension oil ring sets from Total Seal are included with every kit at no additional charge. 9310 alloy .210" wall wrist pins are included with the Extreme Duty series. Recommended clearance: .003" for mildly boosted and .0035" for highly boosted measured .850" from the bottom of the oil ring groove. \