The PRO 150 comes with a separate, interchangeable pre-filter. This means you can replace the pre-filter by itself without having to replace the entire multi-layer filter. In a few seconds your air purifier goes back to peak performance. This is mainly useful for hair salons where there is lot of hair floating in the air.
For individuals and small businesses, note that the pre-filter is already integrated in the PRO 150 replacement filter.