This thumb operated M3 Nut is specifically manufactured for hotbed levelling of 3D Printers. It is designed to be operated by hand without the need for any other tools - spanners, pliers, etc. Can be easily rotated by the hand to adjust the level of the headed. The screw is standard M3 size and has a large diameter head for easy operation by hand. Its large diameter compared to normal nuts also lets you do fine adjustments on the headbed.