Interchange or swap your V2 or V3 Fusion Engine into an M249/M240! This was made by Bingo Airsoft and includes everything you need minus the Fusion Engine and FCU. Includes TCU for automatic box mag winding, FCU cable, UPB, and pre-wired and mounted trigger switch. If you have any questions feel free to message me. No trades, thanks. Thank you for looking and have a great day.