Attracts and captures microscopic particles such as smoke, cough and sneeze debris, bacteria and viruses—and large particles, including lint, household dust and pollen. Outperforms fiberglass, washable and non-electrostatic 3-month pleated 1″ home air filters for your furnace, air conditioner, or HVAC system. Filtrete 1550 MPR (Microparticle Performance Rating) equates to MERV 12. Lasts up to 12 months. 20 x 20 x 4