That is old K&T wiring. As stated the loom was used when the single conductor wire turned corners. When wire was run in a straight line paralel to the floor joist, the K&T would rest under the individual knobs or when the crossed through the beams then the ran in the tubes. When you were running from the ceiling and wanted to turn down a wall. They electrician would slide the loom over the single 14 ga RH wire. It prevent the wire from chafing on the wooden beams. Here in northern NJ there is still a lot of K&T wiring in homes around here. Also as stated the loom would protect the singel strand wire when it entered a box.
