GSA Advantage Listing 

A washable cotton pre-filter surrounds the main filter in the Austin Air HM400 or HM450.  It gets the larger pieces of dust to prolong the life of the more expensive HEPA filter.  It can be hand-washed but most users throw out the old one after a year and install a new one.  To change filters, the unit is turned upside down, four screws removed, and the old filter pulled out. It is a fast and easy process.

The Pre-filter for the HM200/250 is ClearFlite Part No. 8016.

It works in both 110volt and 220volt models.