Apparatus for leading cables through a wall aperture of a switchgear cabinet, comprising: - at least one seal element, - at least one strain-relief element, and - a housing for attachment to a wall of the switchgear cabinet in the region of the wall aperture arranged in the wall, wherein the housing has the following: - a fastening region which is arranged on a first side of the housing and has fastening means for fastening of the housing to the wall of the switchgear cabinet; - a sleeve region which is arranged on a second side of the housing and has at least one cable insertion opening, the latter serving for laterally receiving the at least one seal element and a cable which is led through the seal element; and wherein the strain-relief element is fastenable to the housing in order to fix the cable to the housing; wherein - the at least one strain-relief element is fitted to an inner side of the sleeve region, and - the housing has a fitting window through which the strain-relief element is actuatable, wherein - the at least one strain-relief element comprises at least one screw by way of which the cable is fixable to the sleeve region of the housing by means of a screwdriver passed through the fitting window, wherein the housing, with its fastening region and its sleeve region, is formed in one piece, wherein the apparatus has a cover which matches the fitting window and by way of which the fitting window is able to be closed off by screwing, wherein, at the edge of its window, the housing has a flange rubber seal such that the cover, in a closed state, particularly effectively seals off firstly with respect to the flange rubber seal and secondly with respect to the consequently slightly compressed seal element and the latter also with respect to the cable led through, characterized in that the first and second sides of the housing are situated opposite one another, and in that the housing has the fitting window on a side of its sleeve region that is situated opposite the aforementioned inner side. - at least one seal element, - at least one strain-relief element, and - a housing for attachment to a wall of the switchgear cabinet in the region of the wall aperture arranged in the wall, wherein the housing has the following: - a fastening region which is arranged on a first side of the housing and has fastening means for fastening of the housing to the wall of the switchgear cabinet; - a sleeve region which is arranged on a second side of the housing and has at least one cable insertion opening, the latter serving for laterally receiving the at least one seal element and a cable which is led through the seal element; - a fastening region which is arranged on a first side of the housing and has fastening means for fastening of the housing to the wall of the switchgear cabinet; - a sleeve region which is arranged on a second side of the housing and has at least one cable insertion opening, the latter serving for laterally receiving the at least one seal element and a cable which is led through the seal element; and wherein the strain-relief element is fastenable to the housing in order to fix the cable to the housing; wherein - the at least one strain-relief element is fitted to an inner side of the sleeve region, and - the housing has a fitting window through which the strain-relief element is actuatable, wherein - the at least one strain-relief element comprises at least one screw by way of which the cable is fixable to the sleeve region of the housing by means of a screwdriver passed through the fitting window, - the at least one strain-relief element is fitted to an inner side of the sleeve region, and - the housing has a fitting window through which the strain-relief element is actuatable, wherein - the at least one strain-relief element comprises at least one screw by way of which the cable is fixable to the sleeve region of the housing by means of a screwdriver passed through the fitting window, wherein the housing, with its fastening region and its sleeve region, is formed in one piece, wherein the apparatus has a cover which matches the fitting window and by way of which the fitting window is able to be closed off by screwing, wherein, at the edge of its window, the housing has a flange rubber seal such that the cover, in a closed state, particularly effectively seals off firstly with respect to the flange rubber seal and secondly with respect to the consequently slightly compressed seal element and the latter also with respect to the cable led through, characterized in that the first and second sides of the housing are situated opposite one another, and in that the housing has the fitting window on a side of its sleeve region that is situated opposite the aforementioned inner side.