... , nitrided, chrome plated etc 3.OEM&design service offer 1.piston ring for cummins 6bt and other models(6ct,m11,nh220 ... ,nh250c,nt855,k19 etc);2.Material: nodular iron, cast iron, steel, alloy, and etc(we can do as customer ... quality and best service and ex-factory price. 8. cummins piston ring series details as following:GOLD TRUTH NOModel/ Engine/OEM ...