The magnets were (so attachment of posters to magnetic blackboard) purchased for use in the classroom. This purpose they fulfill perfectly so far. One of magnets held in the endurance test laid a stack of 24 sheets of A4 size. That's more than enough for my needs. The size is pleasant, the game characters design enhances handling. Since the magnets are open, I go carefully in order and make sure that they do not collide too violently (with neodymium magnets, one hears often of higher risk of breakage). Here might be a completely enclosed in plastic magnetic beneficial. Since I had no problems so far this circumstance, I will forgive the perfect score and would recommend the magnets.
