I have just had a look at this sight on the website you mention and as you say there is no technical info on it,other than it has optical quality glass. It ought to have a very small m.o.a. dot for that price, but with no info I would be dubious in parting with that amount of cash. It would appear to be rugged enough for firearms use , but if you are using it on air guns then you are paying a premium for features that you don`t need.
I have had good performance from red dot sights for under £50.
Pete.