Baltic,Germany,

Russia,Ukrain and most Ex-USSR (∅ mm.)

USA, Canada

(approx)

Great Britain

(approx)

Switzerland

(approx)

France

(approx)

India

(approx)

Japan

(approx)

15

4¼

H½

7.5

47.4

7

7.5

15.5

4¾

J

8.75

48.7

9

8.5

16

5½

K½

10.5

50.6

10.5

10

16.5

6

L½

11.75

51.9

12

11

17

6½

M½

13.25

53.1

13

13

17.5

7¼

O

15

55.1

15

14.5

18

7¾

P

16.25

56.3

16

15.5

18.5

8½

Q½

18.25

58.3

18

17

19

9

R½

19.5

59.5

19.5

18

19.5

9¾

T

21.5

61.4

21.5

19.5

20

10¼

U

22.75

62.7

23

21

20.5

11

V½

24.75

64.6

25

23

21

11½

W½

26

65.9

26

24

21.5

12¼

Y

27.75

67.8

28

25.5

22

12¾

Z½

29

69.1

29

26.5

22.5

13¼

Z1

30.5

70.4

23

14

Z3

32.25

72.3