The design of the Cooler Master RC-311B-SWN1 Elite 311 Red ATX Mid Tower Case comes with three external 5.25” drive bays, two external 3.5” drive bays, and five 3.5” internal drive bays to install hard drives, optical drives, and other essential components. It provides housing for any ATX or micro ATX motherboards, and supports your future PC system with a pre-installed 120 x 25mm fan. For optimal cooling, it is also designed with additional ports for two 80/90mm and two 120/140mm fans.