Set of 4 Sensory Cylinder Blocks: : This sensory set contains 4 wooden blocks with 20 knob cylinders that vary in height and/or diameter, allowing toddlers to practice matching the correct cylinder to the correct dot. This allows the child to distinguish the correct depths of the cylinders. Develops Children's Visual Size Discrimination: : The knob cylinders introduce visual size discrimination, refining the child's perception of dimension and preparing for mathematical activities such as comparison, classification, and seriation. The blocks provide error control, so even a young child can use them successfully. For Classroom and Homeschool: : The depth discrimination cylinder block is perfect for toddlers 36 months and older. It is intended to be used in conjunction with single-shape puzzles after the child has mastered the pincer and palmar blocks. A great addition to any homeschool or for travel. DIY Teaching Tool for Ages 3 and Up: : These size discrimination blocks are made of environmentally friendly solid wood. Crafted in such a way that it has no sharp corners. They come with natural wood color, but parents can work with toddlers in DIY colors (like 2 in blue, 2 in red, 2 yellow, 2 green) and make them into wood-colored cylinders. Helps the child distinguish colors in addition to shapes and sizes. 12-Month Quality Guarantee & 30-Day Refund Policy: This set of natural wooden blocks comes with a 12-month quality guarantee. If for any reason you are not satisfied with this toddler toy, you can return it within 30 days of the purchase date for a full refund, no questions asked.