Matched Gearbox by Bravo Airsoft Heat-treatedPrecision 8mm Bearing wellsStandard Japanese 8mm Bearings 8x3x2.5mmHard-Coated with Trivalent Chromium (Cr III)Gearbox features high impact tolerance, durability, and strength making it perfect for your super high-speed and super high-FPS set ups.

Classic Army's Version 2, 7mm Type gearbox differs from other standard 6mm gearboxes in that the bushing holes are larger. These gearboxes are primarily designed for high-speed use in MP5's, however can also fit all MP5 (Except MP5K and PDW), M16, and G3 Series airsoft rifles.

This is ICS's "Upper Gearbox B" reinforced M120 Upgrade Kit.  This kit includes all of the parts needed to build out a fully reinforced upper cylinder for your ICS PCR-97/M4A1/M16 type airsoft rifle.The kit includesn all of the following parts:ERICSMA34 Upper gearboxERICSMC39 M120 SpringERICSMA46 Metal spring guide(II) with screwERICSMA50 Tappet plate and with springERICSMP23 BoltERICSMC19 Piston headERICSMC05 Full teeth aluminum piston*For ICS series M4/M16 type AEG's only.

Systema Complete Mech-Box for M4, M4 RIS and S-System type airsoft rifles. This gearbox set comes with the Systema M120 spring and Systema Torque-Up Gears installed and tuned.

Broken your stock Marui V2 gearbox? Looking to upgrade? In either case, you'll need one of these as a replacement!

UTG's gear box assembly for UTG M14 style airsoft rifles.  Also works with TSD Tactical M14 airsoft rifles.This product is the core gearbox assembly and includes all components inside the shell.  For replacement, additional disassembly is not required.

Reinforced metal gearbox (Version II) For MP5/M16/G3 Series AEGs.

Echo 1 Complete replacement gearbox for the Echo 1 E90.

Systema Complete Mech-Box for G3 type airsoft rifles. This gearbox set comes with the Systema M100 spring and is tuned for high-speed applications. Completely replaces your exsisting gearbox.

Systema Complete Mech-Box for G3 type airsoft rifles. This gearbox set comes with the Systema M120 spring and Systema Torque-Up Gears installed and tuned.