All these magnets are considered to be made of the highest-quality rare earth minerals on the market. They’re made of an alloy of neodymium, iron, and boron. This alloy, most commonly referred to just as neodymium, produces the highest-strength permanent magnet, or magnet with a force that is still present in the absence of an electric current (unlike an electromagnet, which turns on and off with an electric current). These magnets are also made with nickel or nickel-copper coatings that protect them from rusting and other wear-and-tear. Since iron is part of the neodymium alloy, corrosion is possible if the coating gets chipped or otherwise compromised.