MAC Studio Fix is a pressed powder foundation. It comes in a sturdy black compact with a good size mirror and a separate compartment to hold a sponge for application. Personally, I use a buffing brush to apply as I think it gives a better finish. I use shade N5, which has neutral undertones.
I do like this for days when I just want a tiny a bit of coverage and shine control. I have heard it can be built up to a medium coverage, but I always fear looking powdery.
All in all, I really like this for sheer/light coverage and shine control. It's also nice for hauling around in your bag for touch ups.