- Compact 15" Depth. - 1.6mm Steel Body Chassis. - Shock Absorbing Drive Cage. - Front Access USB2.0 x2. - 120mm x1 Cooling Fan. - Removable Air Filter. - Fan and Temperature Monitor Option. - Industrial Keylock Bezel. iStarUSA Rugged E-40 rackmount chassis is designed to withstand the toughest and compact environment. E-40 is 4U height with only 15" in depth and special features of front USB access, ball-bearing cooling fan, and system sensor board to enhance functionality and usability for critical missions and applications.