Neodymium (neo) magnets are popular for their extreme strength in a compact size and weight, and for their high coercive force (they are permanently magnetized in temperatures below 590°F). They are a rare earth magnet, and are the strongest magnets in the world – the higher the grade, the stronger the pull force of the magnet. Neodymium magnets are brittle and should be handled with extreme care to avoid personal injury and damage to the magnets. Take care to avoid pinching of fingers between two or more magnets, and do not allow them to “jump” toward attracting magnets. These magnets are NOT for children.