They can be used for both supply and extract application. The ceiling diffusers type DLK-Fb comply with the fire protection regulations without affect on the air technical functions.

The DLK-Fb ceiling diffuser consists of a very stylish square diffuser face with centre screw fixing to the plenum box, the screw head is covered by a decorative cap. An angled fire protection plate is inserted in the plenum box, this is held in the open position by means of a fusible link (release temperature 72 °C). Connection between the ducting system and the circular side entry spigot of the plenum box is by means of flexible hose provided by others.