Shaw-Magnets-Alnico-Button-Magnets-Shaw-Magnets-ALB19-A-19mm-diameter-Button-Magnet-from-Shaw-Magnets-made-from-Alnico-magnetic-material-Alnico-is-an-alloy-of-iron-ALuminium-NIckel-&-CObalt-&-has-a-high-resistance-to-loss-of-magnetism-The-magnet-is-supplied-complete-with-a-keeper-which-further-helps-to-keep-the-magnetism-without-gradual-loss-&-to-protect-the-magnetic-surfaces-The-central-mounting-hole-provides-an-easy-way-of-fastening-the-magnet-to-frames-supports-clamps-etc-