Bravo Airsoft Complete Gearbox for M4 style airsoft guns.  This complete reinforced gearbox is build with all of Bravo's high-grade internals to ensure quality and durability.*This gearbox may be compatible with other AEG's that have Version 2 gearboxes, however the gearbox may need to be rewired to the rear.  Please know that changing the wiring or modifying the gearbox in any other way will void your warranty.

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.

Echo1 M16 Complete Gearbox with MOSFET 7mm Reinforced Gear Box ,7mm Bearing ,Metal SPring Guide ,Metal Gear Set ,Metal Tooth Piston Body ,Alum. Cylnder ,Ported Polycarb Piston Head ,MOSFET LOW Resistance Wiring Harness (to the back/ M16 style) ,

The Echo 1 replacement gearbox for Echo 1 M4 style airsoft guns.  This is a complete gearbox, fully assembled to be a drop in replacement for repairing or upgrading your Echo 1 M4 or other front wired airsoft guns which are wired to the front and require a Version 2 gearbox.  *If you have any questions regarding this gearbox, please contact us prior to purchase.

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

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

Echo 1 Complete replacement gearbox for the Echo 1 E90.

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 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.