These super strong magnets are perfect for buttons to turn into fridge magnets. perfect for 23mm, 28mm and 38mm buttons. They are easily glued to the back of a flat back button (or take shank out). Use e6000 glue available in the craft section. These are 20mm diameter and 3mm thick, packed in bag of 10. They fit perfectly into a 23mm button but also can be used on 28 or 38mm. Magnets cannot be sent airmail overseas, must go by ship.