Matrix "QD Fast Spring Change" 8mm Gearbox for M4 M16 Airsoft AEG (Model: Front Wire)

"Excellent gear box for the money, buy this if your looking for a micro switch and a QD spring.
If your interested in the internals:
+Great high quality gear set
+robust and reliable micro switch
+quality gearbox shell
+good wires
+good spring
and for the bad things:
-its cylinder, cylinder head, piston head, and air nozzle are all just about trash.
this is the only downside but this is always somthing specific to your airsoft gun however so its an often replaced item as i planed to replace them anyway, and i dont consider it as much of a downside and i think the box is an excellent deal

"This is the best gearbox ever!!!
I put a m140 in and used a matrix magnum motor.

PROS:
This shoots hard and fast with a 9.6v
You dont need to take the whole gearbox apart
To put a better spring in

CONS:
Not really any i put it in a friends PDW and i had
To file parts out but its over all good.

"I love the quick spring release so u don't have to take apart the whole gearbox, and I also lik the trigger response. To me there is nothing wrong with this product. Really reliable.

"This is the Airsmith's dream gearbox for the M4/16 platform.
Please note that although this is a great Mechbox to start off with it does have some issues...

1st off it will NOT fit in a G&P or a KWA body without mods, but this it to be expected because both company's use parts made just for their brand.

2nd, if you plan on upgrading this with a stronger spring, or change the gears, do yourself a favor and get a new piston pronto, as well as a new air nozzle. they are both plastic and cheaply made and under high stress they will fail.

Other than that I have to say I love the bushing/bearing combo. Bearings where needed for a high speed setup and bushings on the gear that can not have wobble.

All in all this is a great box for the price.....

I have mine installed with 13:1 Super High Speed Gears, A High Speed piston with AOE modified with a sorbo pad, running a Tornado Motor, pushing a Prometheus M115 spring.

Cronoed with .25s at just under 300 FPS (360ish with .20s) but ROF is over 30 RPS!!! I had to get the High feed mags to keep up with this speed beast!!!

"This is a superb concept in gearboxes! I wish they had always done them this way! However it is only made for an M4, you cannot swap out normal Ver. II selector plates or switches! The new switch is a great design and in my opinion doesn't necessarily require a mosfet in most cases unless you use a lipo. The gears and piston that come with it are more for speed then power but the spring swap-out is flawless. You may require some custom fitting and if your stock needs to screw into the block on the back you may have an issue? I can't tell for sure because I bought this trying to convert it for an MP5 and it will not work! I rate this box perfect for around 400 FPS. This is great all around but do not try and convert it for anything but an M4 because you can't!

"its a good build box and it was really easy to work with the internals, but it it would take a few shots and stop, it would act like the microswitch would work then stop but once i took the gearbox apart and put it together it would work again. Besides this problem the box is great but once i put it any of my receivers it does not like it.
:( to bad it did not work, it just means more parts for me