A fitting and an associated grommet are provided for supporting a conduit penetrating a panel and limiting energy transfer between the conduit and panel. The fitting may include a grommet having annular first and second sections spaced apart from one another and an annular wall extending between the first and second sections such that the wall and first and second sections define a bore. A plurality of ribs protrude from the annular wall, the ribs being distributed circumferentially around the annular wall and spanning between the first and second sections. A tubular liner extends through the bore of the grommet and contacts the first and second sections. The plurality of ribs extend into the bore, and at least some of the ribs contact the liner.