An adapter that terminates 5/16 tube into an AN6 female 37° flare connection. It suits builds where a section of the run is done in hard line for neatness and protection — along a sill, chassis rail or firewall — before transitioning to flexible hose. Note the size relationship: 5/16 tube into an AN6 seat means the tube is the smaller of the two, so this combination is best where the run does not need the full AN6 bore. The tube must be flared to 37° with the proper tool, as the shallower 45° flare common in general automotive work will not seal against an AN cone.