The SRC 6MM Complete Gearbox for MK36 is the best way to upgrade your gearbox. 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 6mm 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 3 MK36 AEG
Package Includes: Complete Gearbox
Airsoft GI recommends professional installation for this product.