You will need to tinker with it...
When i got the gearbox it said on the box that it came with a motor. ASGI said it didn't, so i wasn't disappointed when i got the gearbox and there was no motor. (though i think there should have been a motor with the gearbox.)
the gearbox is metal with metal internals, a plastic nozzle, (the reason i got a new gearbox, more on that later) and pretty cheesy wiring. Dont get me wrong, the wiring works fine, but you might want to keep that in mind.
Ok the reason i got this gearbox is because in my jg m16 (it uses this gearbox) broke. The reason it broke was two fold. firstly, i was using cheap bbs. DO NOT USE WALMART BBS. second, a friend of mine was using it and when it jammed he kept firing it instead of clearing the jamb. this broke the nozzle that pushes the bb into the barrel and directs air flow. I repaired it with a spare nozzle I had lying around, only to break it again, (still trying to figure out how) only when I went to repair the gearbox the second time i must have put it together wrong cause it was making weird noises and not firing properly.
Now for the actual gearbox:
when i put it in my m16 the pins that go through the gearbox and into the body of the m16 would not fit. The reason for this was the holes in the sides of the gearbox were not drilled large enough. It was a minor fix, but still, you'd think that they would have better quality control. I have not chrono'ed it yet, but it seems to be shooting around 350-380fps. RPM is fairly high with an 8.4v 1500mah battery but i have a pretty good motor too. All in all, I would say its an ok gearbox but you might want to go ahead and spend a little more and get a better brand gearbox.
rear wired, (for m16. You will need the wire extensions from the m16 so keep those because this gearbox does not come with the wiring)
easy to install
Needed a fair bit of minor tinkering (drilling out holes)
plugging the wiring into the wire extensions was a real pain. You might need to get some LARGE heat shrink tubing to secure connections.
its a basic gearbox. it will work but not the best by any means.