the factory tube is 500cc 52mm 14 inchs long that comes on the karma eq this one fits the karma eq cause i put it on mine its 350cc and only 10.5 long 3 and half inchs shorter than factory on the full length eq i have since put a 250cc 7 inch long tube on my rifle makeing it a compact and no longer need this tube i payed 85$ for the 7 inch tube from the pellet shop i just trying to move this tube it will work on other aea rifles also