This diffuse box is designed to provide hygienically pure air in facilities where filtered air is important, such as in operating theaters or industrial clean rooms. The diffuse box features four types of plenum, the choice of which depends upon the installation restraints that may be encountered at the site. Ceiling height can also be a factor. Air flow rate can be adjusted from 150 to 1400 cubic meters per hour. A wall-mounted version is available and each diffuse box contains guide rails that allow easy insertion and removal of the unit's filters.