The smallest are 12 x 3 mm, they are about 1/2 coin in size. We use them to display different sizes of images on a 4' x 8' white electroplated sheet. Four of them in the picture seem to work well enough that they're barely noticeable. It is also good for sticking notes, shopping lists, and for children to play and create shapes, etc. Some refrigerators and various types of metal alloys are not attracted so much, this is not the magnet's fault.
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