100pcs 10 x 3mm Hole 3mm N50 Strong Ring Magnet D Countersunk Rare Earth Neodymium Magnets Permanent magnet 10mm x 3mm Hole 3mm 100pcs 10 x 3mm hole 3mm n50 strong ring magnet d countersunk rare earth neodymium magnets permanent magnet 10mm x 3mm hole 3mm