Hi Bruce, I think they are  alnico magnets- they look just like the ones in speakers. I must have 30 of them stuck to the  door in my barn waiting for them to tell me what they want to be!! I did put handles on a  few and use them to hold up stuff on cabinets in my shop. They are pretty huge for refrigerator magnets, though.

Cheers, Jim ........................ Variety is the spice of life...............Learn something new every day