Prevost Replacement Filter - MFM - Mechanical Micro-FiltrationThe Prevost MFM Filter is a Mechanical Micro Filtration Filter. It filters particles that are 1. 00 m or larger. This is a replacement cartridge filter for the Prevost 3 Stage Combination Sub Micronic Filter. Over time, you will need to replace the filters to ensure that the air quality through your system is what it should be. It is recommended that you replace this filter every 6000 hours or once per year. What makes these filters great is that they