The kit for renewal of piston rings, code P51706-03, provides all essential components needed to restore optimal sealing and compression performance in the MAN L21/31 engine. Piston rings are critical for maintaining combustion efficiency, regulating oil consumption, and ensuring proper heat transfer from the piston to the cylinder liner. Over time, rings wear due to high pressure and thermal cycling, and this renewal kit ensures a complete and precise replacement process. By restoring tight sealing and reducing blow-by, the kit contributes to improved engine efficiency, lower emissions, and extended service life—an indispensable maintenance solution for engines operating under heavy marine or industrial loads.