Double Bell Complete 8mm Ver. 2 Gearbox for M4/M16 Series Airsoft AEG - Rear Wired

"This is a decent gearbox. Probably not as good as the Systema and G&P, but the pricing is GREAT. All the part intact are dboy stock, which is not bad, similar by Classic army will cost you three times the price.

A gearbox will virtually never "break". It is composed of approximately 20 different parts that will cost you over hundreds to buy separately. Each part might wear off thru out time depending on usage, and you just need to replace them, all the parts are sold pretty cheap here at Evike and available, thus a gearbox never breaks.

"This is the first time I noticed in all the gearboxs ive work with, that the sector gear does not have enough clearance from hitting the cylinder. It may be a design flaw or it could be just mines. Even without shims on the sector gear, it is too big for the gearbox to close properly. I have to file down the area were the bearing sits in order to work, otherwise it will be too tight. The gearbox comes with a lot of upgraded parts but these flaws I mentioned above is enough to ruin a gearbox. The parts are good but the shell itself needs quality control.

I can see why the Facebook comments are having jamming issue. This is most likely why it will not work if you just drop it in without checking the gearbox.

Hope this review helps

Pros
Upgraded parts
Good compression
Metal teeth piston
Strong standard gears

Con
Gearbox shell design flaw

"This gear box is OK, you would need to replace the plastic bushings with metal. Most gear boxes version 2 are pretty much the same. The internal parts are important. Does it have metal bushings, metal bearings, or by the MM size of the bearings or bushings. Bigger is better in that case. Also, you want to look at piston guild, does it have bearings, or is it just a guild. Then piston itself, does it have a metal gear stripe in the center or is it just polycarbonate. Those are the things to look at when buying a mechbox. The internal strength of the parts inside. Best for just buying a solid mechbox is the JG Golden Eagle! Has everything metal, that needs to be strong. Very good deal for $70.00 if you bought the parts to build a box like it, it would cost over $100.00 Good luck, keep shooting!