ProTeam 6qt Triangle Shake Out Bag - This is the inner cloth filter bag which goes into the vacuum body first and then the paper disposable bag goes inside the cloth filter bag.  Make sure this is always installed to give your vacuum even better filtration and as a fail safe in case the paper disposable bag fails and nothing gets into the motor of your vacuum.  The cloth filter is also washable so when it gets dirty just take it out, wash with warm soapy water and let air dry.