7 Pack Replacement Filter Pads Designed to Fit with MicroPower Guard One Hour Cleaner Frame Size 20x25x1 Actual Filter Szie 18.5"x17.5" Activated FULL CARBON CENTER / Ozone free / Made in USA Replace Every 1 to 4 Months: Depending Local air quality for optimal performance. CAUTION: Do not place order using the measurement of disposable fiberglass pad. Measure the outside frame or refer to filter label inside plastic channel. The products advertised on this page are manufactured by Fast Shipped Filters. Fast Shipped Filters is a family-owned business in Swanton, Ohio that has been in the Heating Cooling & Air Purification industry since 1984 MicroPower Guard One Hour, Natures Home and Xenon Power Guard is a registered mark of Clockworks IP, LLC. Fast-Shipped-Filters is not affiliated with Clockworks IP, LLC.​ 7 Pack Replacement Filter Pads Designed to Fit with MicroPower Guard One Hour Cleaner Frame Size 20x25x1