Features 1、Super strong rare earth magnets, once stuck to each other, it is difficult to separate 2、Suitable for DIY projects, such as whiteboard fixing, adsorption of various steel parts, fixing tissue boxes on the roof, etc 3、Very suitable for putting notes on the refrigerator door.Used in speakers, receivers, microphones, sirens, stage sounds, car audio, etc 4、Used in electromagnetic relays, sound level meters, reed switches, sensors. VCM, CD/DVD-ROM, generator, servo motor, micro motor, electric motor, vibration motor 5、Applied to magnetic machinery. MRI scanners, magnetic health products, etc. Magnetized wax, pipe derusting, magnetic fixing devices, magnetic locks, door and window magnets, magnetic suitcases, leather magnetic toys, tools, gift packaging Specification Item Type: Round Magnet Material: Iron D12 x 3 Specifications: Diameter: Approx. 12mm / 0.5in ,Thickness: Approx. 3mm / 0.1in For M4 Counterbore: Small Hole with a Diameter: Approx. 4 mm / 0.2in ,Large Hole with a Diameter: Approx. 8mm / 0.3in Package List 20 x Round Magnet