a housing having a housing body and a rotor housing disposed in the housing body for screws of the screw compressor, wherein, in an operationally ready and assembled state of the screw compressor, an oil sump is provided in the housing body, a baffle plate is arranged in the housing body below the rotor housing, and a magnet formed as a substantially cylindrical disc is arranged in the oil sump below the baffle plate,

an air inlet for feeding air to be compressed to an air filter,

an air feed channel for receiving filtered air from the air filter and supplying the filtered air to screws of the screw compressor,

a valve insert disposed in the air feed channel to regulate supply of the filtered air to said screws, and

a drain plug removably coupled to the housing, wherein the drain plug is movable from a closed position to an open position, wherein an oil outflow opening is closed when the drain plug is in the closed position and wherein the oil outflow opening is opened when the drain plug is in the open position,

wherein the magnet is fastened to the housing by a spacer passing through the magnet, the spacer being composed of a screw bolt and a distancing sleeve pushed onto the screw bolt, and

wherein the magnet is arranged in the housing body and is spaced away from an inner wall of the housing body so as to permit oil to wash completely around the magnet except for a region of the magnet at which the spacer passes through the magnet, wherein the magnet is spaced apart from, and not connected to, the drain plug and/or the oil outflow opening, and wherein the magnet is maintained in the housing body when the drain plug is moved to the open position.