1. Weight: about 50g/piece 2. Size: about 7.5 x 5.5cm 3. Material: Plastic 4. Applicable age: children over 4 years old 5. Features: it can perform operations such as addition, subtraction, multiplication, division, and size comparison. It can not only be practiced by children, but also can be tested by parents, and learn in entertainment. It is ever-changing, which not only develops people logical thinking ability, but also enhances practical ability, exercise the coordination of brain and hands
