This versatile tool is used together with the Unifix Interlocking Cubes (sold separately) to demonstrate and understand number concepts, base 10, and operations through to 100.  The base measures 23 cm (about 9") wide and has ten positions for building stacks of the interlocking cubes.  Also included is a 100-grid backing card and 22 number label cards for 10, 20, 30, 40 and 50.  The set also comes with a comprehensive teacher's guide with illustrated activities for number relationships, addition, subtraction, multiplication and division.