Abstract: Angular sections form frames which can be fitted together in the frame plane in modular fashion. Legs of the sections are formed so that through two interconnected legs of adjacent frames notches of T-shaped cross-section result, into which hammer head-shaped ends of pull rods can be introduced. By means of the pull rods, ledges can be pressed against filter and/or light fixture housings, which in this manner are pressed against legs of the profiles on the opposite housing side, adjacent frames thus make it possible in a correspondingly compact model to attach filters and light fixtures without the distance between two adjacent filters or between a filter and a light fixture occupying a width that would impair the flow profile of the air issuing from the filters.