Should be a set of 3 but I only received 2. On the other hand, the ones I received work great. The magnets are strong and you have to align them properly so they grab each other, but it also keeps them from slipping off. It will be just over 1/2 inch in diameter. I think it's a bit expensive, almost $10. A set of 4 for the same price would be a great buy.
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