If your commercial ozone air purifier is not emitting as much Ozone as it used to the first thing to do is carefully remove the plate clean it with warm soapy water rinse and allow to dry before reuse. If that does not work then the next thing to do is buy a new plate here. 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 Ammonia. Features: 4.5 x 6.5 inches; Ceramic with stainless steel Mesh; Package includes 1 large ozone plate. These plates will only work on the commercial purifiers with the metal body.