It came as a part of a deal a long time ago with an M4 I bought (around last summer) for my birthday. Seeing as it came as part of a package, it was mostly free. As other people said, the front cover barely stays on, there are no instructions, and it's pretty cheap feeling. Something nobody else seemed to mention is the fact that IT DOESN'T WORK! If you go outside with it, you can hardly see the tiny dot it produces, and the green is completely invisible at most times.
My friend got http://www.airsoftgi.com/product_info.php?cPath=36_340&p-
roducts_id=4651 that sight for his MP5, and since he didn't buy the correct mounts for it, I've been using it and it's outstanding if you're in the market for optics.
Free (for me) with a package
Looks sort of cool
DOESN'T SHOW UP
No instructions on how to zero
The knobs needed to be turned to zero it are bad
Very nonresponsive when zeroing
Pretty cheap feeling
Rating: [2 of 5 Stars!]