Our Pro Tru line of pistons utilize a plasma moly pre-gapped ring for the budget minded consumer. Wiseco Sport compact kits include the high quality NPR XX rings, which are the best quality steel nitrided top rings and napier style 2nd rings. Our late model EFI lineup and several small block Chevy pistons are designed around the our 1.2mm Steel Nitride and napier GFX rings. Many of our big blocks utilize a .043 back cut top ring for extra material thickness around the intake valve.