Oakio Iniwood decking is the first generation of wood plastic composite [WPC] products. The result is a dense, heavy, and weather resistant products that won't splinter, warp, rot, or split. High quality hard wood fiber [Oak wood] and high density PE resin are the main raw material....http://www.woodure.com/wpc-decking/hollow-composite-mahogany-decking-board143.html