M2/M2.5*L+4
M3/M4*L+6
M5/M6*L+8
M8*L+10
Please note before buying: M2、 M2.5、 M3、 M4 are nickel-plated.
M5, M6, M8 are color-plated zinc treatment
They are made of carbon steel, but the surface color is different!
Size: Thread Diameter * Stud Length + External Tooth Length
For example: M3*10+6