- 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.