I have purchased two of these clamps and received them before the estimated delivery date. The packaging is substantial and the clamps arrived undamaged.
The clamps are well made and work as expected. They are a new twist on an old idea, the Holdfast which woodworkers have been using for a very long time, see photo.
When using the clamp, to get full clamping pressure the clamp must be pushed down hard on the work piece with the cam lever in the reset position. If this is not done the cam has to take up any gap before exerting pressure on the work piece.
When the cam exerts pressure on the work piece it causes the knurled shaft in the dog hole to press against the sides of the dog hole. This pressure is only at the top and bottom of the dog hole as the cam tries to rotate the clamp within the dog hole. The knurled shaft does not need to be knurled all the way round as it only bears on the dog hole where it is in line with the clamp arm. If the knurling was only where needed it would make fitting the clamp in the dog hole easier. If the clamp will damage the dog holes over extended use, only time will tell.

This clamps are very well made and nice to handle.
Proud owner of this quality product.
Thanks Dennis from Hooked On Wood for his recommendation.