When this disposable paper filter bag is 3/4 full, it MUST be replaced. Excessive over filling of this bag makes it difficult to remove from the vacuum tank and can result in breakage and spills. These bags fit the Mastercraft Enviromaster hazardous waste recovery vacuum, and they come 5 per pack. When removing the paper bag if you recovered any hazardous materials, you need to carefully remove the bag, and wipe down all surfaces with a disposable rag. Place the disposable paper filter bag and damp cloth in a OSHA approved poly bag, and dispose of it in accordance with the local hazardous waste regulations.