It appears to me that the one you describe is simply a "rest" for the chain saw... Unless I'm misreading the pictures, the clamp(s) to hold the logs are already installed in the pictures.
I'm in the U.S. and have not seen a device like this. My immediate reaction (having thousands of hours on the working end of chainsaws) is that the things made of steel... long lasting enough, but one would have to be very careful as one reached the completion of cutting through the logs not to let the saw drop dow just a few inches and strike the supports under the rack. This would ruin your whole day.
Here we just use a slap together wooden "sawbuck" like this:
http://www.wikihow.com/Build-a-Sawbuck-for-Cutting-Firewood
Cheap, efficient and doesn't damage the chain if it slips and strikes the sawbuck... Easily repaired s well...