Review on Circular Holes Ferrite Ring Magnets by Stephen Cernatescu

These strong magnets are great for science classes. The hole is big enough for a pencil to allow the magnets to levitate. My only complaint is that they break easily! 24 students used them for 20 minutes just trying to run the magnet to see if the magnet's attraction would go through their desk (pass), if they could pass the paperclip and transfer the magnet's attraction to the paperclips , without the magnet. Nothing caused the magnets to fall off, and yet three groups came back to me with broken magnets after handing out 24 magnets, two to each pair of students. the students felt bad and I know they didn't try to break it. Magnets are just not physically strong. If you use this as a teacher for teaching, please buy extra!