Eclipse Magnetics M19082NK Alnico Button Magnet, 4 lb. Pull Capacity, 3/4" Diameter x 1/2" Height Button magnet made from Alnico Grade 5 material, unpainted color of gray, with one mounting hole (screws not included) with a maximum temperature of 550 degrees C Diameter tolerance is +/- 0.031", thickness tolerances is +/- 0.05" Come keepered (non-magnetic metal plate) to reduce damage 0.75-inch diameter, 0.5-inch thickness, 7/32-inch mounting hole Maximum pull of 4 pounds