These unique disposable vacuum bags are meant to be used with the EDIC 10 quart backpack vacuum, or the discontinued lead abatement HEPA recovery vac. They come in packs of 5 and when you purchase in bulk, we do offer additional discounts. When the bag becomes full, you will start to feel a loss in suction, and that is when you know the bag needs replacing. Simply take off the top of the backpack vacuum remove, throw away, and replace.