These large Rare earth magnet discs are crazy strong. Only purchase these neodymium magnet discs if you know what you are doing and well versed in handling very powerful neodymium magnets. Two of these stuck together are virtually impossible to separate by hand. They can pinch quite hard and cause physical harm if they are not handled with extreme care and respect. One of these permanent magnet discs has a pull force of over 90 lbs if attached to a steel plate.