One of my bike friday bikes came with the 1/4" NPT pipe welded to the frame.
One came with that little adapter. I can take any photos you like, although you should be able to work on the dimensions from the tubing size on the bike.
I did use the adapter on my old Colnago, but it seemed to have worked itself loose on the tapered rear stay tubing. I believe the BF tubing doesn't have a taper, so that shouldn't be an issue.