Here you will find all Grada perforated ceiling diffusers with side entry spigot with insulated plenum and adjustable supply air! These diffusers are ideally suited for a 600x600 suspended ceiling. The air supply is adjustable via the four separate dampers! The ceiling diffusers have a side entry spigot with insulated plenum and are available in different diameters. Because of the insulated plenum less heat is lost. The perforated ceiling diffusers have a panel perforation of approximately 51% and are made of steel. Still looking for another diffuser? Then take a look at our full range of ventilation grilles!