WE-Tech Complete Full Metal Gearbox for M4 / M16 Series Airsoft AEG Rifles (Model: Rear Wiring)

"i fixed he issue with the anti reversal latch not releasing you need to dremil of file the front of the tooth and make it flat so it rest against the latch when running other whys it locks into the bevel gear to tightly i posted how to fix on youtube https://youtu.be/Aubh5PTBNJ4 original post is for the katana but the lower gearbox are almost identical

"Very nice gearbox, you cant beat the price with how high quality it is. I dont think its the normal 1:3 gear ratio because im using the same motor as my old gearbox and the rate of fire is now really fast. Re-shimming always recommended but I didnt re-shim mine, the factory shim job was flawless. If you buying this for a JG m4 ABS body, it is a very tight fit. the claw that connects to the anti reversal latch so when it goes in safety the latch disengages just jams up because the receiver body is not wide enough. You can file the inside if the body or simply take the claw off like I did, then shoot in semi once to decompress the piston spring. Nice job this gearbox is awesome for the price!

"Great gearbox for the price. Out of the package it was shimmed pretty nicely, though reshimming is always recommended. It is front wired and it doesn't come with a plug on the front of the wires so you will either have to buy one or use a spare one.