Hollow Blocks16 piece set constructed using Baltic birch and northern hardwoods. Edges are rounded and surfaces are sanded smooth for safety and hours of creative play. Blocks are sealed and finished inside and out. 54 lbs. set. These smooth unit blocks are made to resist dents and dings. You'll notice the finely sanded and rounded to eliminate any sharp edges, and are splinter free to protect tender young hands. All our blocks are guaranteed for life. Materials,