Description
M8 Nut.
1.25 mm pitch (standard).

Error Tolerance
Prints great, however be warned if your Z axis is not calibrated it will not work very well. This can be a compounding error. Every (Z)1.25mm the Z axis error is added. There is 5-6 threads in total, so an error of 5% for example will put the last thread .25mm out of place.

The X & Y axis are far more forgiving.