The modular design of the LSS Dimmer Duct 250 x 140 allows a dimming system within a duct system. The inside of the duct is prepared for circuit boards, which can be fixed by slots and/or screw fastenings. The duct is used as a heat sink for the dimmer modules, which surface is magnified by the large cooling fins at the bottom. The cover opens downwards and can be removed in a specific angle. On the cover are two sections, one for devices and another for connectors. They can be placed according to the needs.