# 39-20058  Mercury Piston Ring   STD 20-40-60ci. Piston rings for KE7, KF7, KG7, KG7H, KG9, KH7, Mark 20 & 20H, Mark 40 & 40H, Mark 25, Mark 55 & 55H, Mark 35A, Merc 300, Merc 350 (4cyl), Mark 75. These are new Hastings Piston rings. 1st in piston ring technology, a long established American company. Ring material is HR45-97 cast iron, (218174CX). Rings are manganese phosphate coated. Hastings rings are top quality, you can't buy any better.  We have now depleted our supply of Mercury NOS standard rings. We are switching over to HASTINGS Piston Rings.