These permanent, oriented Ferrimag Ceramic Magnets have a high energy output of up to 3.4 megagauss oersteds. Use barium iron oxide magnets for holding devices, loudspeakers, generators. Ground within precise tolerance and meets with MMPA standards. Rectangular magnet measures 152 x 102 x 25 mm. We also offer a smaller magnet that measures 75 x 50 x 25mm. Magnetized on largest dimension.