The super-strong rare-earth magnets are great for DIY projects and perfect for sticking notes on fridge doors. The magnets are electrically conductive so they are suitable to extend recessed batteries. They are super strong rare-earth magnets - once they get stuck with each other they are hard to break apart. - Note : due to new postal shipping regulations DX is now adding significantly more packaging material to pack these super strong magnets. This also ensures safe and speedy delivery of the magnets. . For significantly better value a 100-pack package is available. . - Super strong RE (Rare Earth) magnet -- once they get stuck with each other they are hard to break apart - Electrically conductive (making them suitable to extend recessed batteries) - 2mm thick 20mm in diameter