The StarTech.com 12cm x 12cm x 2.5cm (4 3/4\" x 4 3/4\" x 1\") PC case fan is an add-in cooling fan designed to fit most computers. It can be used to circulate cool air into the case or exhaust warm air out, preventing problems due to overheating components. A quiet running brushless ball bearing DC motor coupled with a high efficiency blade design is capable of moving 48 CFM (cubic feet per minute) of air. Power is supplied to the fan using a standard LP4 (hard drive power connector) pass through plug.