If you aren't sure what your piston ring groove sizes are, call the piston manufacturer or have the grooves measured by a machinist with accurate measuring equipment.
Optional Napier cut on the second ring can slightly reduce friction on the second ring while providing a more positive scraping edge to keep oil and combustion gases separate all while keeping the thicker portion of the ring in the ring land for better strength and rigidity.
NOTE: These are special order ring sets intended for turbocharged 3SGTE based engine builds and as such are ordered in a higher tension and custom made per your selected options. We can not stock all options and all sizes, so these will be special ordered. Allow 2-3 weeks for delivery. No returns accepted on these ring sets. These are NOT gapless rings -- rather higher quality custom made conventional ring sets. Filing of the ring gaps will be required per the included guidelines included in the box of rings.