Size Comparison Chart

Standard (US) Size Internal Diameter European Size
3 14.0 mm -
3.5 14.4 mm 46
4 14.8 mm 47
4.5 15.2 mm 48
5 15.6 mm 50
5.5 16.0 mm 51
6 16.45 mm 52
6.5 16.9 mm 53
7 17.3 mm 54
7.5 17.7 mm 56
8 18.2 mm 57
8.5 18.6 mm 58
9 19.0 mm 60
9.5 19.4 mm 61
10 19.8 mm 62
10.5 20.2 mm 64
11 20.6 mm 65
11.5 21.0 mm 66
12 21.4 mm 67
12.5 21.8 mm 69
13 22.2 mm 70
13.5 22.6 mm 71