Denotes whether the model has a disposable bag. A growing number of vacuums, particularly upright models, use a container that can be emptied, eliminating the bag. To capture fine-dirt particles, however, these models must use a filter (such as a HEPA filter) that can need routine cleaning or replacement. Replacement filters tend to be significantly more expensive than bags. While vacuums with bags may also use filters, the bag acts as a prefilter that helps to keep the fine-dirt filter cleaner, thus extending its performance until cleaning or replacement. Another caveat: Emptying the dustbin and cleaning a filter can be messy, and handling it may expose you to dust and other allergens.