I bought this hop-up unit for my G&G Sportline GR16 Blowback to give my gun more accuracy and a full metal hop-up along with my new tightbore barrel. It is very well constructed and felt solid. The bb catch is nice and I can take my mag out anytime without bb's spilling everywhere. However, there is always one bb left which is kinda annoying but it isn't to bad. The adjustment wheel is much better than a regular M4 hop-up. The bad thing was for some reason, the Madbull Blue Bucking wouldn't fit in the chamber and after hours of work, I finally had to actually cut the bucking partially to get it to fit which was annoying. I would only reccomend this to people who know what there doing.
Solid construction out op metal.
Good accuracy with Madbull Blue Bucking. (w/ crappy Crosman .20's, I was getting an effective range out to 125+ feet)
Chamber lock function.
Can mount a tracer unit.
Adjustment wheel is better than a standard M4.
Increases fps some.
A bit of QC with the fitment of the bucking.
Not good for beginners.
A bit pricey.
Overall, I was quite happy with this and I would buy it again.
(Side note: I could put a G&G Green Bucking in the hop-up without a issue)
Rating: [5 of 5 Stars!]