Fillers and reinforcements are used to change and improve the physical and mechanical properties of plastics. Fillers and reinforcements may also be used to lower material costs by reducing the volume of matrix resin required. Fillers are used to modify or enhance properties such as thermal conductivity, electrical resistivity, friction, wear resistance, and flame resistance. There are two basic types of fillers: conductive fillers and extender fillers. A conductive filler is used to increase electrical and thermal conductivity. An extender filler is used to reduce material costs. Fiber reinforcement significantly affects the properties of the compounds to which they are added. Reinforcements are specialized particulates, fibers or fabrics used to strengthen or toughen plastic, metals or ceramics.