D-400S3-2535M4SA is an ultra compact industrial rackmount chassis with 13.7” in depth. The full size I/O supports all ATX motherboard and up to seven full-height add-on cards. Four external 2.5” hot-swappable trayless drive bays are convenient to swap hard drives for maintenance. One 120mm and 80mm cooling fans in the front and two optional 80mm fans can be mounted in the rear to provide the best ventilation to prevent critical equipment from heat damage. D-400S3-2535M4SA provides server or cluster maximum reliability and performance.