This 54-piece Red/Blue set is ideal for aspiring architects and engineers. The precision cut blocks of wood are CPSIA certified green, crafted from New Zealand pine. The distinctive simple shape and light weight of the blocks make them ideal for solo play or for family fun with adults and siblings. Through play with blocks grownups can introduce young builders to architecture, history, mathematics and science with memorable and successful results. Citiblocs uses certified water-based colors to highlight the natural toned pine planks, and they are "stained" as pine naturally absorbs water based colors.