Jims’ Twin Cam Piston Ring End Gap Tool is designed to test ring gaps with a patented cutout feature. The tool possesses a flanged shape that allows the piston ring to fit squarely into the cylinder bore every time. The tool serves Harley-Davidson and Jims engines with various bore specs. To install it, place the tool into a cylinder bore and put the piston ring onto the tool. This tool is made in the U.S. and is also supported by a lifetime warranty.