These are small rare earth magnets - 0.25 inch cubed. Composed of Neodymium/Iron/Boron (NdFeB), these magnets are curiously strong and make for a great way to attach tools to a metal workbench, hold small children to a fridge, and as a trigger for reed switches.

Activates the reed switch at a distance of about 3cm.

Sold in single units.