Piston rings suit Norton ES2 16H - +0.040 oversize (set of 3), 80mm bore. Made by Gandini (GPM). Suits Norton models 16H, 18, 20, ES2, CS1, 30 from 1931 to 1955. Ring height 1.58mm (0.062inch), 4mm (0.157inch) Original Norton part number: 9182; A2/161 - piston ring x 2 for 16H, 18, ES2, 30 9183; A2/162 - scraper piston ring x 1 for 16H, 18, ES2, 30