Just a quick over view of what to expect on this dslr matte box. This particular one is fairly well made with just a few quirks, but it's definitely a hundred times better than the cheap plastic one floating around. If you're really into the aesthetics of your rig, I suggest going for this. The FilmCity MatteBox is mostly metal including the flags, top sunshade, 15mm clamp, and donut ring. The hood itself is the only thing made from hard plastic.
The flags on the Mattebox will not fold up for storage, but it breaks down quickly to be packed away. The top flag will tend to get loose with constant positioning and would require the allen key to re-tighten. The side flags can easily be tightened by hand through the thumb screw. The single filter slides in an out with ease, and can be locked down quickly. It does not rotate so it's not something to be used with a CPL. The mattebox does not have a swing away design, so to make things simple, keep it at the end of your rail set. Yes it does require rails to mount. If you've got the money, I suggest going for the more expensive versions with a swing away design and the ability to rotate filters. One that some consider is by TrusMT found here: Trusmt DSLR MatteBox Carbon Fiber or Aluminum.
Considering the prices of current matteboxes, overall the FilmCity is one of the cheapest with decent quality build (again much better than the uber cheap plastic one). Can be found on eBay (click here).
Inexpensive Single Filter MatteBox with Full Flags