材质 
M6
1
4.5
4.425
4
3.9
6
2.5
M8
1.25
6
5.925
5.4
5.3
7.5
3
M10
1.5
8
7.91
7.2
7.1
9
4.5
M12
1.75
8
7.91
7.2
7.1
10
4.5
M16
2
12
11.89
11
10.9
12
5
M20
2.5
15.5
15.39
14.4
14.3
14
5.5