Yellow Mountain Imports Standard Classic Abacus, Soroban Calculator, 10.5 Inches, 17 Column Lightweight functional tool; the soroban or counting tray is a classical form of the abacus; the abacus is a calculating tool that was used for centuries before the adoption of the written modern numeral system; it is still widely used by merchants, traders and clerks in certain parts of the world Educational tool; in addition to being a professional tool, the soroban or abacus is also an educational tool; the abacus is widely used in teaching children counting and mathematics; people who become proficient in the use of the abacus almost automatically become adept at mental calculation; instructions are not included Standard design; this soroban abacus has a plastic frame; its classical, standard design allows for its ease of use as a professional and educational tool Specifications; this is a 17 digit professional soroban abacus that measures 10.5 x 2.5 x 0.75 inches (26.5 x 6 x 1.5 centimeters) 30 day return policy; we want you to be satisfied with your purchase; you are backed by our 30 day no questions asked money back return policy so you can buy with confidence