Symbol

Surface 

OD mm

Thread 

O.D.(mm)

Distance (mm)

M06

M6

≤ 4

6.0

1.00

M08

M8

≤ 5

8.0

1.25

M10

M10

≤ 7

10.0

1.50

M12

M12

≤ 9

12.0

1.50

1/4

1/4

≤ 4

6.35

1.20

5/16

5/16

≤ 5

7.94

1.41

3/8

3/8

≤ 6

9.3

1.55

7/16

7/16

≤ 7

10.1

1.76

1/2

1/2

≤ 9

12.4

2.06

F-1

T-1

PF1/8

PT1/8

≤ 6

9.728

0.9071

F-2

T-2

PF1/4

PT1/4

≤ 8

13.157

1.3368

F-3

T-3

PF3/8

PT3/8

≤ 10

16.662

1.3368

F-4

T-4

PF1/2

PT1/2

≤ 12

20.955

1.8143

F-6

T-6

PF3/4

PT3/4

≤ 16

26.441

1.8143

F-8

T-8

PF1

PT1

≤ 22

33.249

2.3091