Training kid's visual discrimination of high and low, big and small. Large wooden knobs for easy grasping; | Small size: Include 4 sets cylinder block with socket, cylinders varying in height and/or diameter in each block, Measurement of each socket: 5.8*1.6*1.4in; | Through observation, logical reasoning, analysis and other forms of thinking, help children learn to reason, draw conclusions; | This montessori material can be used as teaching tools in school, homeschool, or early childhood development; | Your purchase is backed by our exclusive 30 day manufacturer warranty - we will offer a free replacement or refund if any defect caused during product production and delivery.