pompeii3

regular

Inside Diameter (mm)	USA / Canadian Standard	British, Irish, Australian Equivalent
14.9	4	H
15.3	4 1/2	I
15.7	5	J 1/2
16.1	5 1/2	K 1/2
16.5	6	L 1/2
16.9	6 1/2	M 1/2
17.3	7	N 1/2
17.7	7 1/2	O 1/2
18.1	8	P 1/2
18.5	8 1/2	Q 1/2
18.9	9	R 1/2
19.4	9 1/2	S 1/2
19.8	10	T 1/2
20.2	10 1/2	U 1/2
20.6	11	V 1/2
21	11 1/2	W 1/2
21.4	12	X 1/2

All Sizes in Inches Unless Otherwise Stated