10pcs N50 Super Strong Block Magnets 20x10x4mm Hole 4mm Rare Earth Neodymium FeaturesShape : Rectangle with centre boreMaterial : NdFeB magnetic materialsProduct Size : (Measurements allowed error)(length*width*height) 20*10*4 mm (diameter of bore) 4mmGrade : N50Quantity : 10Usage:1. Acoustic field: the speaker， receiver， microphone， alarm， stage audio， car audio and so on.2. Electronics: permanent magnetic actuator vacuum circuit breakers， magnetic relays， meter， sound meter， a reed switch， sensors.3. Electrical field: VCM， CD / DVD-ROM， generators， motors， servo motors， micro-motors，motors， vibration motors.4. Machinery and equipment: magnetic separation， magnetic crane， magnetic machinery.5. Healthcare: MRI scanners， medical equipment， magnetic health products and so on.6. Wedding corsage badges， etc.， can be replaced with a magnet attractsevery other clothes pins， so as not to damage the dress.7. For the overlying metal drawing board for fixing the drawing paper. Magnetic blackboard whiteboard fixed file drawings.8. Advertising magnets available to replace the original fixtures， at any timeconvenient to replace the ad content.9. Models piling， you can use small magnets to connect two widgets.10. Studio， bulk magnet can be used to adsorb screws and other parts， even wrenches and other tools! WarningThese magnets are very powerful which should be handled with great care.Do not allow children to play with them unsupervisedas they could get injured.Especially pay attention to the samll magnets ， please place in somewhere children can't reachCare should be used when handling two magnets as they can pull together with such force that pieces of the magnets cansplinter off and cause injury. Keep the magnets away from pacemakers and magnetic storage devices such as mobilephones， bank cards and computers.The Seller will not be held liable for any damage or injury caused by these magnets.Package include10 Magnets /a pack