I must say, this is one of the best hop-ups I have ever owned, it works incredibly well, and I would highly recommend it to anyone looking for a new ho-up. First off, it's very nice in the fact that the adjustment wheel is very large and easy to adjust, and no future adjusment required unless to personal preference, and second, it will fit behind the bolt of the m4. To put it ogether is easy on the paper, but the bucking is very hard to get on the barrel, and is a bit too long, like 2mm too long, and the nub is even harder to get in, but once it is in, it works very nicely.
few parts for putting together
big adjustment wheel
added 20ft range to my gun
easy to adjust with gloves on
bucking is a tad too long, but no bigproblem
hard to get the nub in, but other than that, good hop-up
Rating: [5 of 5 Stars!]