These aren't just any magnet clips to fasten your kids' artwork to the refrigerator: these Endo Magnet Clips are "a solid mass of neodymium, silicone and steel" that can hold up 16 ounces of whatever. You push the circular area and the clip opens up, and then you can securely attach anything that weighs less than a pound.
Those must be some strong magnets, taking considerable strength to remove them from that metal surface. We've heard that word neodymium before—it's used in speaker systems and earphones. The Endo Magnet Clips are available in lots of purdy colors, and they're just 10 bucks for three.
Product Page [The Endo, LLC]