2 Ozone Plates Alpine Ecoquest Living Air Purifiers by V.S.L.A. Compatible with ALL MODELS of: Alpine - Better Living - Healthy Living - Ecoquest - Living Air - Lightning Air - Spring Air - Natures Air - Zen Living - Atlas - Horme Purifiers Measures 4.5" x 4.5" Based on Usage, Our Top Quality Ozone Plates are made to be used anywhere from 2 - 4 Years. We suggest if you have your purifier running all day every day you clean it once a month with Amonia.