Mercury Piston Rings - Used - STD.  20-40-60 ci motors.  2.441 bore, 2 7/16".  P/N 39-20058.  KE7, KF7, KG7, KH7, MK20, MK25, MK20H, MK55 & 55H, Merc 300, 350 4cyl & KG9 - MK75.  Used rings, who would put used rings in a motor? Truth is more people would than you think. If you are just putting around on the lake they work just fine. Trick is the face of the ring that makes contact with the cyl wall must be without rust & scratches. With a little elbow grease and a scotch brite pad these rings are good to use.  84 Available