Scott Atwater antique outboard motor new old stock piston rings.  Aftermarket Sierra brand sold through NAPA Auto Parts Stores. Part number #18-4031. These fit all the 16hp Scott-Atwater outboards made from 1950 to 1957 and possible later.  2 11/32nds by 3/32nds.

Black iron with pin cut ends as original. There are three rings per piston.  Sold in packs of three.  We have three boxes of three.  Look at the photos and email with questions.  Thanks for looking