Window regulators are assemblies for raising and lowering the side windows. They are driven manually or electrically. A typical assembly of electric window regulators consists of guide rails, window brackets, electric motor, Bowden cables, cable drum and pulleys. Both ends of the Bowden cable are connected to the cable drum in opposite directions and are wound up or unwound depending on the direction. Since the Bowden cables are firmly connected to the window brackets, which in turn run up and down in the guide rails, the pane moves. For safety reasons, an anti-trap protection is integrated. Operation is via push-buttons in the interior panelling. In addition to the outer skin and the interior trim, door modules are components of modular vehicle doors. They serve to integrate mechanical, electrical and electronic function modules. An exemplary structure consists of a carrier plate, window regulator, lock module, exit lamp, loudspeaker as well as wiring harness, control units and seals. The structure and equipment can vary greatly depending on the manufacturer and model. Modern door modules are often available in several hundred variants and are produced just-in-sequence. In lightweight solutions, they are made of glass fabric-reinforced polypropylene. According to Brose, in lightweight solutions the door modules alone save 350 grams in weight compared to classic plastic door systems. Door systems are used by OEMs for passenger cars as well as commercial and special vehicles.