The SRC 8MM Complete Gearbox for M4 is the best way to upgrade your gearbox to shoot high a FPS, ~400. The purpose of the 8mm ball bearings is to reduce the friction put on the gears fulcrum while spinning. Don't make the mistake of thinking the only way your gears can break is at the teeth. High power springs with mediocre bushings or bearings can break the gears at the stem. A break at the stem is potentially more dangerous to the gearbox than just a few teeth breaking off. The SRC 8mm Complete Gearbox is designed to prevent damage to the gears and to prevent gearbox failure due to high stress. Stop worrying about which parts are compatible with what, or how to shim. SRC has done all the hard work for you.
Material: Reinforced Steel
Design: Version 2 M4 AEG
Package Includes: Complete Gearbox
Airsoft GI recommends professional installation for this product.
2010-09-14 15:38:27 J. MCLEOD verified buyer Product Information:
I was looking for something to replace my TM gearbox and i hit this and thought it was perfect. So i bought it and it is very nice. It is all reinforced and i am pretty sure it can handle a 11.1v. When i received it i saw that it came with an upgrade spring that makes it shoot 400 fps. I don't recommend putting this in because it will cause more tension in the gearbox and it will not have as fast as a ROF. I was very impressed with the ROF it has with a 9.6, the trigger response is really nice and smooth. Highly suggest!