Geonox Airsoft got to check the licensed Colt M4 Hornet Blue Fox AEG from Cybergun... "In this video we take a look at the Cybergun Colt M4 Hornet Blue Fox. It is a SAEG (Semi Automatic Electric Gun). It is operated with a battery. We are over 0.5J here, so only semi no full auto, so only single fire and from 18.
The Blue Fox has an ETU (Electronic Trigger Unit) and a mosfet. The ETU protects against gearbox jams. The mosfet protects the internals and improves the response.