||If you know what you're doing this gear box is very easy to install.
In fact even if you don't know that much about the inner workings of your gun you most likely have the brains to install this. If you don't and insist on getting this anyways Evike has videos on how to install it, so you can pretty much install this if you know how to use a screwdriver and can follow directions. lol
Things you need to know about this box is that the wiring sticks out the back about an inch or two at the max, so go ahead and put some wires in your cart now. lol The wire that comes out the back is a small type connector so make sure to get the correct wires.
This gear box has an m160 spring and from what I have studied/heard is that stands for 160 meters per second which converts into 524.9 feet per second! Yes you read correctly, 525 fps. This gear box will turn your m4 into an automatic bolt action sniper rifle. lol It is ridiculously loud which can be taken as a pro or a con.
Of course you will have to swap out your stock motor for a magnum/high torque motor. If you're going to put a spring in your gun meant for a pogo stick make sure you have a proper motor and battery.
I installed a Matrix 3000 motor and bought a 11.1 lipoly for this gun. A 9.6 will work for the gun, I've tried it but the rate of fire will be laughed at. Lol
To be fair I haven't tested the longevity of this gearbox, so I can't give an honest estimate to how long it will live.
This gearbox should be used with a full stock or fixed stock, because the pipe on your LE/cranestock will not go over the wiring. I have a crane stock and had to Jerry rig some wiring to make it work, but it is possible.
The response time on the trigger is awesome, it's the way airsoft triggers are meant to be.
The power of this spring cracks .2 gram non bio degradable bbs in half almost every time, so I recommend using at least .25's if not .28s.
From 65 feet away I was shot in the back with this gun (so that way people can't complain when I shoot them) It tore skin worse than any airsoft gun I have been shot with, I bled for a little while.
Obviously do not buy this gearbox if you play on professional fields, because this is almost 200 fps over the legal limit.
I bought this, I don't regret it, it shoots really strong, it's terrifying, and now I have a home defense weapon. lol jk
Rating: [5 of 5 Stars!]