Larry and Earl, we found these in a university remodel. At first I wasn't sure either, but we found that they were mounted to floor duct through a nipple and the 1" RMC coupling that you see in the picture.
You can see the two screws that hold the top canopy on the fitting.
When the top is removed the devices can be wired (by the way this is a duplex receptacle, there is one on the other side too) and then the wires pulled back as the devices are fit back into their place in the fitting.
Roger
