later I needed a pair of strong magnets to stick in a 3D printed prototype I was designing. They fit my project perfectly. What I liked about these magnets is that they are not fragile. In fact, I glued two of these to a small piece of PLA plastic and then realized I had to remove them. Using a screwdriver, I had a hard time prying the edges of the magnets open. The good news is the plastic holding the magnets broke off but not the magnets themselves. - Would buy again without hesitation.