An object of the present invention is to provide an improved and simplified filter assembly. The object is achieved by a dielectric rod (120, 610, 620) for a filter chassis (110). The dielectric rod (120, 610, 620) extends between a first end (121) and a second end (122). The dielectric rod (120, 610, 620) comprises a conductive element (150) placed at the first (end 121). The conductive element (150) is adapted to be in conductive contact with a first contact means (141) of the filter chassis (110). The dielectric rod further comprises a second fastening element (160) placed at the second end (122). The second fastening element (160) is adapted to be attached and detached to a first fastening element (131) comprised in the filter chassis (110), such that the dielectric rod (120, 610, 620) is replaceable in the filter chassis (110).