12 months & up. Wooden Rainbow Architect Arches and Squares include 14 sizes of nesting beech wood blocks. Use for stacking and open-ended play as they lend themselves to STEM concepts like construction, spatial reasoning, patterning, as well as inspiring creativity, language, and design skills. Perfect with the other Rainbow Architect products to extend play even further. The colors in the set are red, orange, yellow, green, blue, indigo, and purple. Arches measure 1.6"D x 0.7"H to 2.9"H. Squares measure 1.6"D x 1.6"W to 5.8"W.