The StarTech.com 9.2cm x 9.2cm x 2.5cm (3 5/8 x 3 5/8 x 1) Dual Ball Bearing 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 brush less ball bearing DC motor coupled with a high efficiency blade design is capable of moving 37 CFM (cubic feet per minute) of air. Power is supplied to the fan using a standard LP4 (hard drive power connector) pass through plug.