I had left over 1" Diameter aluminum tubing and I needed to store items from a workbench above the worktop. These brackets fasten to the underside of shelving material and the tubing slips into the bracket. There is a hole for a fastener to lock the tubing in place but I haven't needed to do that. Four of these brackets are supporting a mechanics tool box with no problems.
The author hasn't provided the model origin yet.