The M4 machine screw has a thread diameter of 4 millimeters, to put it simply, the M stands for millimeters followed by the size – in this case 4 mm.
On the threaded bit, an M4 would have a diameter of 4 mm.
M4 nuts are 4mm in diameter and should be used in conjunction with the appropriate size bolts for a tight fit. We stock various types of 4mm Nuts such as T-Nuts, Wing Nuts and Standard 4mm Lock Nuts.
The holes are 4mm in diameter, so M4 should just about fit.
They are made from heavy duty carbon steel and come with a nut for tightening metal surfaces together. The M4 machine screw has a thread diameter of 4 millimeters, to put it simply, the M stands for millimeters followed by the size – in this case 4 mm.
M5 screws are easy to fasten and have a variety of uses. These 5mm threaded bolts work with matching nuts and come in a variety of different heads, so there’s something for every type of job.
M6 refers to a 6mm metric screw. The outer diameter of the thread is 6 mm. The standard metric rack screw is actually M6 x 0.1mm.
Typically M3 only refers to the 3 millimeter reference diameter, and other industries may use coarser 0.70mm threads – but in the context of PCs 0.50mm threads are implied .