Check the listing for details. Flanders Air Filters, 14" X 20" X 1" Precisionaire Nested Glass - ( 8 Pack ). Condition: New. Listed at 18.49 USD. Flanders Air Filters, 14" X 20" X 1" Precisionaire Nested Glass - ( 8 Pack ) This is a standard grade furnace filter of the same type that has been protecting furnaces and central air conditioners around the world for over 50 years. The filtering medium is continuous filament spun glass. For peak equipment protection and energy efficiency, these filters should be changed monthly.Protects heating and air conditioning equipment without causing additional strainNested construction allows for efficient storageEach filter lasts up to 30 daysUL Class 2 Shipping Policy:Fast & Free ShippingFast shipping from inside the U.S.We DO NOT ship to Warehouse, Freight Company, Logistic Company, PO Boxes. THANK YOU FOR VISIT OUR STORE!