Vintage lot of 2 Perfect Circle Ring Tools / piston ring expander tools with original box and instruction sheet. Box is marked The Perfect Circle Co., Hagerstown, Indiana, Made in U.S.A., U.S. Pat. #1764146. The included instruction sheet is titled “PERFECT CIRCLE RING TOOL — How to Use It” and shows use for piston ring removal and installation.

Both tools are marked at the base of the ring: 4 5/8 TO +.020. One tool also has 40103 etched/written on the side of the ring. Package has handwritten markings that appear to include 40103, EXPANDER, and other shop/stock numbers, but they are worn and difficult to read.

These tools were used to expand piston rings for installation onto, or removal from, engine pistons. This is a piston ring expander / installer / remover tool, not a piston ring compressor. U.S. Patent 1,764,146 describes this type of tool as expanding a piston ring within a circular collar so the ring can be slipped over the piston while reducing distortion.

Sold as-is for restoration, parts, display, or collection. Please review all photos and verify size/application before purchase.