Inside Circumference (MM)

Inside Diameter (MM)

UK and Australia

Europe

US and Canada

41

13.1

D

1.75

41.6

13.3

D 1/2

2

42.3

13.5

E

2.25

42.9

13.1

E 1/2

2.5

42.5

13.9

F

42.5

2.75

44.2

14.1

F 1/2

44

3

44.8

14.3

G

45

3.25

45.5

14.5

G 1/2

45.5

3.5

46.1

14.7

H

46

3.75

46.7

14.9

H 1/2

47

4

47.4

15.1

I

47.5

4.25

48

15.3

I 1/2

48

4.5

48.7

15.5

J

48.5

4.75

49.3

15.7

J 1/2

49

5

49.9

15.9

K

50

5.25

50.6

16.1

K 1/2

50.5

5.5

51.2

16.3

L

51

5.75

51.8

16.5

L 1/2

52

6

52.5

16.7

M

52.5

6.25

53.1

16.9

M 1/2

53

6.5

53.8

17.1

N

53.5

6.75

54.4

17.3

N 1/2

54

7

55

17.5

O

55

7.25

55.7

17.7

O 1/2

55.5

7.5

56.3

17.9

P

56

7.75

56.9

18.1

P 1/2

57

8

57.6

18.3

Q

57.5

8.25

58.2

18.5

Q 1/2

58

8.5

58.9

18.7

R

59

8.75

59.5

18.9

R 1/2

59.5

9

60.1

19.2

S

60

9.25

60.8

19.4

S 1/2

61

9.5

61.4

19.6

T

61.5

9.75

62.1

19.8

T 1/2

62

10

62.7

20

U

62.5

0.786

63.3

20.2

U 1/2

63

10.5

64

20.4

V

64

10.75

64.6

20.6

V 1/2

64.5

11

65.2

20.8

W

65

11.25

65.9

21

W 1/2

66

11.5

66.5

21.2

X

66.5

11.75

67.2

21.4

X 1/2

67

12

67.8

21.6

Y

67.5

12.25

68.4

21.8

Z

68

12.75

69.1

22

Z 1/2

69

13

–

–

Z1

70

13.25

70.3

22.4

Z2

70.5

13.5

–

–

Z3

71.5

13.75

71.6

22.8

Z4

72

14