I just purchased this in combination with a Calumet Studio Clamp with Grip Head. I use them on set mainly to hold diffusion frames and reflectors (poly boards). The build is good and sturdy (even too much), in facts these are much heavier than the competitors'. This can be a problem sometimes as the weight of the knuckle itself can rotate the arm if not tightened correctly.
One difference that surprised me compared to the competitors' is that the knuckle has small teeth that allow a firmer grip when locked. The downside of this is that the teeth can obstruct the rotatioin of the knuckle and finding the right hole takes more time than on the models without teeth. One final note on the paint, as noted by other reviewers the black paint tend to be scratched very easily.
In conclusion I would say it is a good piece of equipment for the price, the ideal purchase if you want to save money over more expensive competitor's models.