KWA metal outer barrel for RM4/VM4/ERG series. These are proprietary due to the cutout for the hopup chamber. You can use this on a normal AEG but you cannot use a normal AEG barrel on the AEG3s. Threaded 14mm CCW. Measures about 10.3" total length from the very rear of the barrel (this is part #370 from KWA). The pin slots for a front sight are messed up a bit so a KWA front sight wobbles if installed, I wouldn't recommend buying this if you want to mount your front sight via pins.