This King Arms Version II Complete Gearbox is front wiring and designed for M4 / M16 AEG. All King Arms complete gearbox are tested by our techenian and it is ready to be installed to your AEG directly. It equipped with 9mm bearings, silver cords, M4 selector plate and M135 spring.

Ver.II Front Wiring Complete Gearbox for M4 Series - M135