Alloy metal.
United States & Canada UK, Europe & Australia CN/SG/JP HK Switzerland Circumference(mm) 4 H 7 9 46.8 4.25 0.5H 7.75 47.4 4.5 I 8 10 48 4.75 J 9 48.7 5 0.5J 9 11 49.3 5.25 K 10 50 5.5 0.5K 10 12 50.6 5.75 L 11.75 51.2 6 0.5L 11 13 12.75 51.9 6.25 M 12 52.5 6.5 0.5M 13 14.5 14 53.1 6.75 N 53.8 7 0.5N 14 16 15.25 54.4 7.25 O 55.1 7.5 0.5O 15 17 16.5 55.7 7.75 P 56.3 8 0.5P 16 17.75 57 8.25 18 57.2 8.5 0.5Q 17 19 58.3 8.75 R 19 58.9 9 0.5R 18 20.5 59.5 9.25 S 20.25 60.2 9.5 0.5S 19 22 60.8 9.75 T 21.5 61.4 10 0.5T 20 23 62.1 10.25 U 21 62.7 10.5 0.5U 22 24 22.75 63.4 10.75 V 64 11 0.5V 23 25 64.6 11.25 W 25 65.3 11.5 0.5W 24 26 65.9 11.75 X 66.6 12 0.4X 25 27.75 27.5 67.2
