Folds out of the way when not needed, has cut-away to fit over piston.
Doesn't fold completely when RT installed.
It's pretty good for how I have my marker set up (CQB).
When mine arrived, I had to modify where it slides into the rear of the A5's receiver in order for it to fit in properly. It also doesn't fold all the way when a Response Trigger is installed onto the marker. Other than that, no complaints, haven't had any trouble with seeing over it with my mask on.
The folding design gives it a multi-purpose firing platform: you can either go freestyle or Close-quarter Battle (CQB) with the stock folded to the side of the marker, or unfold it for a steady urban battle style.
I say get it if you need it. I more or less got it to make my marker look hardcore, but it's good for a firing style change-up.