材质 
M12
1.75
12.7
13.1
22.2
23
9.4
8.3
M16
2
15.9
16.3
27
27.8
12.3
11.1
M20
2.5
19
19.4
31
31.8
14.4
13.2
M22
2.5
22.2
23
35.7
36.6
17.2
15.6
M24
3
25.4
26.2
40.5
41.4
20
18.4
M30
3.5
31.8
32.6
53.5
54.9
27
25.4