M8 (8mm) Wing Nut

Wing nut with M8 metric thread.

Nut with a pair of wings to enable it to be turned without tools, used where frequent adjustments are needed or part removal can be made quickly at some later stage.

Metric threads are designated with a capital M plus an indication to their nominal outer diameter and their pitch:

This nut is M8 x 1.25 - which means the outside diameter of the male thread it fits onto is 8mm and the threads are 1.25mm apart (the most common thread pitch for M8).