1/4" in diameter. 3pc rare earth magnet 5lb pull. Great hobby magnets.Made of neodymium compound. A neodymium magnet (also, known as a rare-earth magnet) is a powerful magnet made of a combination of neodymium, iron, and boron — Nd2Fe14B. These magnets are known to be installed in angular head motors and computer hard drives. Neodymium magnets are also popular with hobbyists, and a small magnet can have amazing properties — it exhibits magnetic braking when moved near a non-magnetic metal due to induced eddy currents.Neodymium magnets should always be handled carefully.hey are hazardous, being able to pinch skin or fingers when suddenly attracted to a magnetic object. Because they are made with special powders and coatings, the magnets are very fragile and break at temperatures over 150 °C, or if allowed to smash together. When they break, the magnets may break so suddenly that flying pieces may cause eye injury. Neodymium magnets should also be stored away from electrical appliances, credit cards and computer monitors, as damage may be irreparable. Other Uses Include: * Fridge Magnets * Various Holding Applications o Blueprints o Architectural Drawings o Photographs o Speaker Covers * Cabinet Closures / Door Latches * Gauss Rifles * Diamagnetic Levitation * Magnetic Levitation * Slot Car Magnets * Stud Finders * Motors and Generators * Tool and Knife Holders * Magnetic Therapy * Magnetic Water Treatment * Welding Jigs * Magnetic Retrieval - Removal * Magnetic Separation * Security Systems * Electronic Proximity Systems * Classroom Education / Science Projects * Magnetic Badge Holders * Magic Tricks * POP and Store Displays * Magnetic Hooks * Tool Magnetizer * Science Experiments