Ring Diameter (MM)	USA/Canada
14.0 mm.	3
14.4 mm.	3½
14.8 mm.	4
15.2 mm.	4½
15.6 mm.	5
16.0 mm.	5½
16.5 mm.	6
16.9 mm.	6½
17.3 mm.	7
17.7 mm.	7½
18.2 mm.	8
18.6 mm.	8½
19.0 mm.	9
19.4 mm.	9½
19.8 mm.	10
20.2 mm.	10½
20.6 mm.	11
21.0 mm.	11½
21.4 mm.	12
21.8 mm.	12½
22.2 mm.	13
22.6 mm.	13½