super quality piston ring: 1. nodular iron, iron, alloy 2. polishing, plating, oxidation 3. ISO9001 4. OEM service super quality piston ring: Specification: Material Cast iron / Ductile cast iron / Alloy cast iron / Multielement alloy cast iron / Nodular iron / Steel / Alloy and etc (we can do as customer's request) Diameter From 68 mm to 160 mm Surface treatment Polishing, plating, oxidation, ...