The StarTech.com 8cm x 8cm x 2.5cm 3 18'' x 3 18'' 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 32 CFM cubic feet per minute of air. Power is supplied to the fan using a power tap that is connected to the large LP4 power connector on a PC's power supply.