4"x4" High Frequency Ceramic Purification Plate. Refer to the original owners manual for instructions. When to Clean: The plate should be cleaned every 30 days. You can use the Ozone Plate Cleaning Kit to clean the Ceramic Purification Plate. How to Tell if it's Working: When the air purifier is on, the purification plate can be detected by smell if it is working properly. Compatible with: EcoQuest Eagle 3000 Alpine Air XL-15 Alpine Living Air Classic XL-15 Alpine Ozone Blaster GreenTech Environmental GT3000 Mercola Pure & Clear EcoQuest Fresh Air 1.0 EcoQuest Fresh Air 1.5 EcoQuest Fresh Air 2.0 EcoQuest Fresh Air Everest EcoQuest Living Air Classic EcoQuest Ozone Blaster Triad Aer