Don't waste time or money on NcStar
Save your money. I had one on my 308 and it just disintegrated in double quick time, but Im also aware of one that is still good after nearly 2 years. That wouldn't persuade me to buy another one tho. Luckily I have a good relationship with my local gunstore and he took it back no questions. I would hate to try and deal with some of the bigger stores in a situation like that.
The NC brand falls somewhere below an entry level Bushnell and slightly better than a seeing-eye dog.
I think Quang Lo used his jizz to glue the lenses into the housing.