Blowers are used in restaurant equipment to diffuse heat, aid in convection, and circulate cold air. A blower is a centrifugal fan. It is a mechanical device for moving air or other gases. Blowers often contain a ducted housing to direct outgoing air in a specific direction or across a heat sink; such a fan is also called a "blower fan", or "squirrel-cage fan" (because it looks like a hamster wheel). These fans increase the speed and volume of an air stream through rotating impellers.