The E-frame has been available in heights for 6U backplanes and now accommodates 3U heights. The unit does not have side or back walls around the card cage area, providing easy access for test and development. The E-frame was designed with the high power and cooling requirements for VPX (VITA 46/48) systems. However, any backplane architectures in a 3U height can be used, including VME and CompactPCI. The total height of the portable E-frame is approximately 9U, with a convenient carrying handle on top. With a rugged modular aluminum construction, the E-frame tower can support up to 21 slots at 0.8? or 17 slots at 1.0? pitch. There are front accessible test points and monitoring LEDs for +3.3 V, ±5 V, ±12 V, ±24 V, and ±48 VDC.