Forged Super Duty series for the Milwaukee Eight engine. With hard anodized crown and top ring groove to reflect heat and prevent ring to groove ''micro-welding''. The Line2Line abradable self-lubricating powder coating technique allows zero tolerance installation; final tolerance will be 0.003". The piston creates its own perfect tolerance during run-in; the coating automatically gives the tightest possible & perfect piston to cylinder fit for no piston rock and best possible ring seal. Note: Fits 114/117" M8 engines; cylinder must be bored to 4.125" big bore size. Case boring is not required; OEM weight so rebalancing is not required and works with stock 4.500" stroke. 10.9:1 CR. (with 88.6cc head volume). Piston weight: OEM. Piston pin weight 115gr.; offset: 0.025". Piston: +1.9cc/Flat top. Compression height: 1.083". Ring pack: 1.2mm 1.2mm 3.0mm. Bore 4 1/8" / Stroke stock 4.500".