Some manufacturers make sure you get 15Kg of wire, whilst some include the weight of the spool. I cant remember the plastic spool weight but I seem to recall it was about 400g.Not sure if it is the same with steel or not as I never use it. With Aluminium however you often only get 6kg per reel with the cheap crap but with likes of Esab or EWM you get 7kg, that makes it not much dearer than the likes of Super6.