Our exclusive math shakers are made of durable plastic, one hinge construction, for ease of opening, and to limit popping open when in use. Our regular dice have rounded corners and roll randomly within the compartments, allowing for quick math practice, especially operational fluency and place value. We have over 100 math activities with our Math Shakers, a student and teacher favorite. Comes with 100 dice (2 flats of 50), enough to fill all 12 shakers with a few dice left over. Several color combinations to choose from.