They feature reduced widths and radial wall thickness in the top and second rings for lower tension and enhanced sealing. The plasma-moly facing on the top ring provides instant seating and long service life. The cast-iron second rings with a tapering open-face profile and open-gap design provide lower inter-ring pressure buildup and excellent oil control. Sealed Power Pro Series file-fit plasma-moly piston rings include very low-tension, thin-profile oil rings that use a wire latch mechanism to simplify installation.