SM-3767 Abacus 

A simple device useful for counting and among the first calculating devices ever used consists of a wooden board mounted base, over which 'U' shaped brass wires are mounted so that the arms of wires are on each side of the board. Each wire has 20 beads (10 each of two colors), which assists in counting and calculations. Available in different configurations (number of rows of brass wire)

SM-3767/1 2 Rows

SM-3767/2 3 Rows

SM-3767/3 4 Rows

SM-3767/4 5 Rows

SM-3767/5 6 Rows