Size Guide - Rings

Inside Diameter US/AUS UK Germany Spain France Italy Japan
16.6mm 6 L 52 (16.6) 12 52 11 11
16.9mm 6.5 M 53 (16.9) 13.5 53 12.5 13
17.2mm 7 N 54 (17.2) 14.5 54.5 14 14
17.8mm 7.5 O 56 (17.8) 16 55.5 15 15
18.1mm 8 P 57 (18.1) 17 57 16 16
18.5mm 8.5 Q 58 (18.5) 18.5 58 17.5 17
19.1mm 9 R 60 (19.1) 20 59.5 19 18
19.4mm 9.5 S 61 (19.4) 21 61 20 19
19.7mm 10 T 62 (19.7) 22.5 62 21.5 20
20.4mm 10.5 U 64 (20.4) 23.5 63.5 23 22
20.7mm 11 V 65 (20.7) 25 64.5 24 23