Mahle Rings Performance Steel Napier THM-13 4.105 x .043in .135RW Plain Ring Set

These Mahle Performance Steel Piston Rings are built with a Napier hook design, a notable feature that helps manage oil flow and prevent blow-by. The steel construction offers durability for performance applications. This set is designed for a 4.105 inch bore with a ring thickness of .043 inches and a 0.135 inch ring land width, ensuring a precise fit for specific engine builds.

The Napier hook, also known as a Napier or barrel-faced top ring, is a design choice that helps scrape oil from the cylinder wall on the downstroke and then redirects it into the oil return slots on the piston. This action helps reduce oil consumption and prevent oil from entering the combustion chamber, which can lead to fouling and reduced performance. The steel material is chosen for its strength and ability to withstand the pressures and temperatures found in performance engines.