CP Pistons CPN ring sets offer maximum seal with minimum drag. These high-strength, low-tension CP Pistons CPN ring sets are designed to provide the sealing power that your small bore and sport compact engine's high cylinder pressures demand. Compatible with today's new cylinder materials, the top ring is a steel compression ring that has been gas nitrided for Nikasil and cast iron bores. The second ring is cast iron with a taper underhook groove face that allows you to run a lower tension oil ring. The oil ring is made up of two gas nitride rails with a low-tension expander with a mini-flex vent design. Less friction and more efficiency equals increased performance when you install a set of CP Pistons CPN rings.