US UK/AU FR IT JP Inside Diameter Inside Circumference
5 J 1/2 50 9.5 9 15.7 mm 49.0 mm
6 M 52 3/4 11.5 12 16.5 mm 51.5 mm
7 O 55 1/4 14.5 14 17.3 mm 54.0 mm
8 Q 57 3/4 17 16 18.2 mm 56.6 mm
 
Because sizing and cut will vary between brands, please use this chart as a general guide. If you are between sizes or need assistance selecting the proper size, please contact Customer Service.