A few companies have been showcasing their firearms with this compact carbine stock.
Troy has their M7A1.
LWRC has their PDW
Well this stock is actually made by a Canadian company called North Eastern Arms.
My FFL got one in and I got to play around with it in his garage. I added it to my KRISS Arms M4 stock adapter and put it on his Vector SBR.
The CSS stock looks awesome on the Vector. The only downside is that the two guide rods are too narrow. So the stock cannot collapse all the way. The picture below shows the stock collapsed as far as it can go. If the rods were ground down or channels were cut into the polymer upper, then the stock would be able to close.
At the moment, there are only a few people importing this stock into the US. Troy Industries will be selling it soon.
Here is a video by SMGLee posted last January testing the CSS on a SBR.