Neodymium magnets are the strongest magnets. You can glue these magnets to your projects to make them stay together. Details:Package of 4Nickel-plated magnets.5" (12.7 mm) in diameterWARNING: Magnets can cause medical devices to malfunction. Individuals with internal pacemakers, internal defibrillators and insulin pumps should avoid items containing magnets or magnet closures.