I made the mistake of buying bags for my Zing twice from sellers who claim to be OEM or exact replacement parts. You are not working. They blow the dust off your back! They aren't the cheapest but come in a Bissell box and each box of 5 packs has a pre and post filter. I change filters as soon as I get a new box. Keeps my zing in great shape. PS I live in a house with several cats and I vacuum a lot of garbage.