SPJ: 23 Digit Plastic Standard Soroban Reset Button Abacus 13.70" Arithmetic Mathematic Calculating Tool Size: 13.700.662.55 (inch) / 7.5 (oz) 1 ball (having a value of five) and 4 balls (having a value of one) Because the lightweight and durable it is recommended for children practice. Also, it does not compress the household at an affordable price. It is a very popular item with a useful feature that can be reset at the touch of a button. Merchants from the mathematics education of small children and students, is a full-fledged products that can be used to businessmen.