An interesting comparison of Version 3 gearboxes from Retro Arms and X High Tech/Combat Gear is made by Hokum of Airsoft Ukraine... "From the technical point of view the ultimate difference between these two is in the process how they were made. The X High-tech gearbox is casted first and then milled (or if you prefer - polished with CNC). The one from Retro Arms is completely CNC machined out of the solid block of aluminium AW EN7075 T651.
This X High-Tech CNC 7075 Aluminium Reinforced Gearbox will fit most M4 AEGs, usually the Tokyo Marui-compatible ones. If you're ok with a red-coloured gearbox with what seems to be 8mm bearing and comes with all the small parts you need to complete the gearbox before dropping it in your AEG, you can get this at EB Airsoft for US$119.98, free shipping included.
