Need to help your equipment perform at its peak while reducing your facility's cooling and energy cost? The Srthermduct kit can change a standard Tripp Lite SmartRack 42-48 U enclosure into sealed passive cooling structure that allows heat that is exhausted from equipment to be vented upwards into the facility CRAC/HVAC air return system. The SRTHERMDUCT Thermal Duct Kit can change a standard SmartRack 42-48U enclosure into a sealed passive cooling structure that allows heat built up inside a rack to be directed up and into the facility CRAC/HVAC return air system.