Air Fltr Dust 20x24x1 MPR (Microparticle Performance Rating)&lrm;: 500 Thickness&lrm;: 1" Attracts and captures large particles like lint, household dust, dust mite debris and mold spores, Outperforms fiberglass, washable and non-electrostatic 3-month pleated 1" filters For optimum performance, change your filter every 90 days or sooner