This set of 3 magnets were made with SikaGrout-215 cement grout and super-strong magnets. After curing for 1 month, they were sanded down to be as flat as possible. Some imperfections are expected but they reflect the raw and rustic look. The magnets measure 1.5" x 1.5" (4cm x 4cm) and 1/4" thick. The thickness of each magnets may vary slightly. As I use super-strong magnets, these magnets can hold very well on fridges and magnetic boards.