TROX swirl diffusers of the DCS type with perforated metal cover are suitable for both the commercial and industrial sectors. They consist of the perforated dover panel, the rear swirl diffuser and the plenum box with round duct connection spigots on the side. The addition (induction) of room air and swirling air discharge ensures swift reduction of the supply air temperature differential and the flow velocity. The swirl diffusers of the DCS type are suitable for deployment in systems with constant and variable volume flow in a volume flow range between 100 % and 25 %.