Wirewound resistors are designed to be able to handle high power levels while providing precise resistance values. The resistive wires are wound tightly around a ceramic core, fiberglass core, or an insulated metal. The ceramic or fiberglass material is used to provide electrical insulation, and it also dissipates the heat. Wirewound resistors have a large surface area that allows them to handle higher power loads without overheating. Some wirewound resistances are also encased or coated in flame retardant materials to prevent environmental damage and ensure safety.