Let me start by saying I got this awesome sight from Mike (DiscountAirsoft).
This is a 551 EOtech replica.
It has Red and green reticules and has around 19 brightness levels!
It's very easy to adjust the reticule's place for windage and elevation.
It is also almost completely metal, and feels very sturdy.
It runs off 2 size 357 batteries I believe. Wich are readily available at stores like Wal-Mart and are actually quite good.
It came with a lens cover that fits under the metal "hood" and folds down to cover both pieces of the glass.
The glass does show glare but so far it's not real bad.
The glass is also nice and clear and easy to see through with only a minimal amount of tent so it should work fine for darker games as well as CQB.
It comes in a nicely padded box with ethafoam (I think that's how it's spelled) surrounding the sight to protect it from damage.
It also came with a quick detach lever that you can install if you don't like the standard knob with a slit for a screwdriver or quarter.
I played a game at vanguard with this and it's awesome! I got lots of headshots...However you will probably need a riser rail if you have a full face mask.
Also it has a lot of brightness settings but it does not get bright enough to use in an outdoor game, unless you play in the woods or somewhere other than out in the desert, in direct sun light.
Overall it's a very good sight though, with a nice clear reticule.
The sight
The sight on my G&P CQB-R
