Examine the Gibson logo on the peghead, the part of the banjo where the tuning pegs attach.
This was later changed to the same hex-head screw going through a separate bracket below the plate that was attached to the rim, and still later to a serrated thumbscrew replacing the hex-head screw. The ball bearing tone chamber design is attributed to Lloyd Loar. Thus a TB-5 was a tenor banjo with -5 grade fancy trimmings. Black painted thin rim, chrome, one co-rod. By acting as a tight band around the rim, the tube also added greater structural integrity than competing bracket and shoe models.