Filter Bags (pack or 5) - fleece filter bags for the Attix 33 and 44 models. Despite the capacity difference between these 2 machines, Nilfisk has spec'd the same bag for both. The 33 and 44 come with a plastic disposal bag and have been engineered to work without any filter bag. However, if you're working with any kind of hazardous dust or debris, using the fleece filter bag in conjunction with the main PTFE filter and the HEPA filter provides 3-stage filtration for maximum safety.