Modular units for filter ceilings with vertical laminar flow. It can house both terminal diffusers series ALU-SIDE. It is characterized by a strong rigidity and ease of installation and so it is commonly used in hospital applications. Open central zone to let the shaft of the scialitic lamp go through. It is usually supplied in a single assembled piece, but it can also be supplied in more parts for an easier transport or mounting in the yard. The exhaust section is plane, without projections, in order to allow an effective cleaning with the disinfectant products used in hospitals.