Mahle MS Piston Set Duramax 4.075in Bore 3.898in Stk 6.417in Rod 1.358 Pin -40.7cc 16.8 CR Set of 8The MAHLE Motorsports PowerPak kit is our high volume shelf stock program developed for high performance enthusiasts and sportsman class racers. The PowerPak pistons are predominantly made from 4032 aluminum alloy to allow for tighter cylinder to wall clearances and improved temperature stability. Some applications require 2618 alloy including the PowerPak Plus category. Each kit is complete with a set of high performance rings, containing either a low drag 1.0mm, 1.0mm, 2.0mm set, a 1.5mm, 1.5mm, 3.0mm set, or a 1/16", 1/16?, 3/16? high performance Ring Pak standard with big block kits.