US, Canada	UK, Australia, Ireland, New Zealand	Japan, India, China, South Africa	Spain, Italy, Netherlands, Switzerland	Inside Diameter & Circumference(mm)
4	H	7	6.75	14.88 & 46.8
4.25	H.5		7.5	15.09 & 47.4
4.5	I	8	8	15.29 & 48
4.75	J		8.75	15.49 & 48.7
5	J 1/2	9	9.25	15.7 & 49.3
5.25	K		10	15.9 & 50
5.5	K 1/2	10	10.5	16.1 & 50.6
5.75	L		11.25	16.31 & 51.2
6	L 1/2	11	11.75	16.51 & 51.9
6.25	M	12	12.5	16.71 & 52.5
6.5	M 1/2	13	13.25	16.92 & 53.1
6.75	N		13.75	17.12 & 53.8
7	N 1/2	14	14.5	17.32 & 54.4
7.25	O		15	17.53 & 55.1
7.5	O 1/2	15	15.75	17.73 & 55.7
7.75	P		16.25	17.93 & 56.3
8	P 1/2	16	17	18.14 & 57
8.25	Q		17.5	18.34 & 57.6
8.5	Q 1/2	17	18.25	18.54 & 58.3
8.75	R		19	18.75 & 58.9
9	R 1/2	18	19.5	18.95 & 59.5
9.25	S		20.25	19.15 & 60.2
9.5	S 1/2	19	20.75	19.35 & 60.8
9.75	T		21.5	19.56 & 61.4
10	T 1/2	20	22	19.76 & 62.1
10.25	U	21	22.75	19.96 & 62.7
10.5	U 1/2	22	23.25	20.17 & 63.4
10.75	V		24	20.37 & 64
11	V 1/2	23	24.75	20.57 & 64.6
11.25	W		25.25	20.78 & 65.3
11.5	W 1/2	24	26	20.98 & 65.9
11.75	X		26.5	21.18 & 66.6
12	X 1/2	25	27.25	21.39 & 67.2
12.25	Y		27.75	21.59 & 67.8
12.5	Z	26	28.5	21.79 & 68.5
12.75	Z 1/2		29	22 & 69.1
13		27	29.75	22.2 & 69.7
13.25	Z1		30.5	22.4 & 70.4
13.5			31	22.61 & 71
13.75	Z2		31.75	22.81 & 71.7
14	Z3		32.25	23.01 & 72.3
14.25			33	23.22 & 72.9
14.5	Z4		33.5	23.42 & 73.6
14.75			34.25	23.62 & 74.2
15			34.75	24.23 & 76.1
15.25			35.5	24.03 & 75.5
15.5			36.25	24.23 & 76.1
15.75			36.75	24.43 & 76.8
16			37.5	24.64 & 77.4