The unitech barrels don't fit on the 2012 demon back the threads are too long compared to the stock barrels so you end up with a 6-7mm gap between the end of the barrel and the end of the back which would cause problems hemce why I'l selling them seperate to the marker I can't go lower than £300 plus postage I'm already loosing £250 on a marker I've had since september and a parts kit I've used 4/5 orings from, there's Foot and one other guys that. I've seen with an abundance of spares for sale its a bargain for £300 and I really can't go any lower sorry.