It's plastic. The only metal parts are the bolts holding it on, and the pivot block.
The stock itself is plastic. I expected it to at least be reinforced with metal, but it isn't. Holding it tight to the shoulder causes it to flex, enough that I thought it was going to break. The pivot block seems to be well designed, and I imagine it would function well with a stronger spring and metal-to-metal contact. However, since the arm is pretty slick plastic, I think it just slips. I knew that it was plastic, but I expected it to be metal reinforced like a Choate folding stock.
Additionally, the shell holders are not particularly well designed, and shells slide out within a couple of shots.
My experience with other folding shotgun stocks is limited, but I have never encountered something like this. I am almost certain that the metal stocks from Butler Creek are better.
I may have come across a bit strong in my original post, but I am still a bit bitter about the whole experience, and sorely disappointed with Butler Creek and Remington.