18 months & up. Unit Rocks® have unique design to help children develop cooperation, patterning, creativity, cognitive development, fine motor, and mathematical skills. Built to withstand years of tough play, this set is for building enthusiasts. Each block is hand-carved with deep textured grooves and an organically colored rustic appearance for great sensory play. Encourage children to be creative and build a variety of structures. Use these blocks in a lesson about shapes, and have children create the shapes you discuss. Available in sets of 50 and 100.