Our 16-piece set Mini Hollow Blocks are sized to standard unit block construction. Beautifully constructed with birch plywood and solids, and no exposed screws or hardware. Edges are rounded and surfaces are sanded smooth. Blocks are sealed and finished. For indoor use only. Ages 3+. Largest block measures: 11"W x 5.5"D x 2.75"H. Smallest block measures: 5.5"W x 2.75"D x 1.25"H