WPC are usually: Made of wood fiber/flour and plastic(s). In addition to wood fiber and plastic, WPCs can also contain other lignocellulosic and/or inorganic filler materials. WPCs are a subset of a larger category of materials called natural fiber plastic composites (NFPCs), which may contain other cellulose-based fiber fillers such as pulp fibers, peanut hulls, bamboo, straw, dig estate, etc.