Purpose： This wooden knob log cylinder can effectively cultivate children's visual perception and sensitivity to dimensions, learn to distinguish the size, height, and thickness of objects; at the same time, it can improve fine motor skills and cultivate engineering skills , Space awareness, logical thinking ability and imagination, to prepare for mathematics learning. Packing List： This wooden Montessori toy includes 4 sets of cylinders with sleeves, each of which is fitted into its own hole. Each cylinder has a different height and/or diameter, and the size of each sleeve: 9.05 X 2.2 X 1.9inches. Cylinder 1: The cylinder is different in one dimension: the diameter remains the same, and the height increases. Cylinder 2: The cylinder changes in one dimension: the diameter increases and the height remains the same. Cylinder 3: The cylinder is different in two dimensions: the diameter increases and the height increases. Cylinder 4: The cylinder changes in two dimensions: the diameter increases and the height decreases.