Abstract: A compressed air filter adapter for connecting a filter element (12) to a filter connection housing (13) includes a flow duct (21) enclosed by a wall (20) for compressed air, the flow duct (21) at a first end being delimited by a first opening (14), having an inner contour (142) defined by a first edge (141) and an outer contour (143), and at a second end by a second opening (15), having an inner contour (152) defined by a second edge (151) and an outer contour (153). The first opening (14) is provided for connection to a filter connection housing (13) and forms an opening cross-section (16), defined by the inner contour (142) of the first opening (14). The second opening (15) defines an opening on the filter side and forms a second opening cross-section (17), defined by the inner contour (152) of the second opening (15).