"This US100 was designed by Dr. Leo Richards who was the head of the Soroban Institute in the USA. It is designed for individuals with larger fingers. It is also suitable for the beginner because of the bigger sized beads. In addition this soroban can be used on an overhead projector and the image projected where the image of the soroban can easily be projected onto a screen. You can also use it as a teaching soroban in the class room. This soroban is suitable for addition and subtraction, but is not really intended for work with multiplication and division.