Comes in all new armalite series enhanced/advanced JG guns.
In the stock gun, the full potential cannot be reached unless a metal one piece hop (requires a metal body) and a TBB is installed.
I recommend downgrading to m110-m120 for a m4, you don't need mondo fps in a carbine.
Fine for m16 though a m120 isn't a bad idea if you have strict fps limits.
LIPOLY READY!!!!! It handles a LiPo better than many $300 gearboxes, the gears are great steel gears, $27, but said to pull up to m160 (no way that would work) With the JG high torque m120 motor this gearbox can take a 9.6v 2000 mah battery and run 18 rps with it.
5/5 for price
5/5 for performance
4/5 for need to lower spring rate in many cases
-high fps (may be a con) I get 440+ fps in my m16 with an upgraded hop and TBB
-comes in stock new JG guns
-cheap beyond belief, you could just get this to use as parts if you desire
-high fps, the front wire should be m110 or m120, since carbines and cqb need low fps
-bushings are 6mm (though they look smaller) so they can't handle a big load
-don't get if you have no clue how to take your gun apart
-expect the need to tune or repair in the long run, it is good, but not perfect
-spring has lots of coils and is really loud for some reason...
-you might want to lube this if you are good with gearboxes, just for better performance