Knobless Cylinders

The Knobless Cylinders are four sets of wooden cylinders, each a different color with varying height and diameter as same as the Cylinder Blocks. There are 40 cylinders in total, 10 each per color: The yellow set of cylinders increases in height and diameter, the blue set of cylinders only increases in height with the same diameter, the red set of cylinders only increases in diameter with the same height and the green set of cylinders increases in diameter, but decreases in height.

During the early children days and infancy, especially the sensory characteristics (i.e. size, color, shape, weight, etc.) of an object stimulate them and draw their attention.
Montessori calls this stage "Sensitive Period"
In other words, this period is sensitive time to obtain certain ability for the development of intellectual activity, and at the same time, its formation period.
Therefore, at this time, it is necessary to have the sensory educational objects to stimulate the sense capabilities from outside