39-20058 .020 Mercury Piston Ring 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. You will only find these .020 rings at Outboard Paradise, we have them specially made for us by Hastings. Now, you may ask yourself, what good is a .020 ring when .020 pistons were never made. .020 rings are very handy for compensating a  worn .015 bore. So, if you have a little bit of talent, a .020 ring can be file fit to your slightly oversize .015 bore. Boat racers have been doing this forever. We can provide you with a tech sheet of how to file fit your rings to your cyl bore. So now .020 rings suddenly become very handy to have. We only have a extemely limited supply of these rings as a test.  If they become popular, we will special order more.