Eclipse Magnetics M19186NK Insulated Pot Magnet, 1" Diameter x 1" Thickness, 1/4-20 Thread Size Pot magnet made from Alnico Grade 5 material encased in a steel housing, unpainted color of gray, with one mounting hole and with a maximum temperature of 220 degrees C Diameter tolerance is +/- 0.012", thickness tolerances is +/- 0.010" Come keepered (non-magnetic metal plate) to reduce damage 1-inch diameter, 1-inch thickness, 1/4-20 thread size Maximum pull of 16 pounds; note that maximum pull conditions are based on ideal conditions - variations in iron content, thickness and/or finish & condition will reduce the actual pull achievable