Button Magnets are simply horseshoe magnets in a compact circular format. They are made from alnico to provide a high resistance to corrosion and a high temperature rating. All sizes have clearance holes for mounting. They must not be recessed into ferrous materials as it will short circuit the magnetism.
Maximum operating temperature: 500°C.
The E-Magnets 821 Button Magnet has the following specifications:
Diameter: 12.5mm (1/2 inch).
Height: 9.5mm (3/8 inch)
Maximum Pull: 0.7kg.