21 x 21 x 1 Standard Panel Furnace / Air Conditioner Filter. Case of 12 filters. Actual Dimensions 20 5/8 x 20 5/8 x 3/4 For large volume orders please contact our Business Sales department at 1-877-852-6133. Lead times may vary due to the volume of your order.The Glasfloss GDS disposable panel filter features an innovative reinforced double strut construction for excellent durability and performance in commercial industrial and residential applications. The new design provides 10 greater open media area than traditional metal grill filters and offers excellent dust holding capacity. In addition the new design allows for easier disposal and eliminates sharp edges for safer handling. These filters utilize a double-skin progressively dense fiberglass to maximize dust holding capacity. The media and strut retainers are glued and sealed inside a one-piece craftboard frame made of 100 recycled materials. The filter frame is clearly marked with size UL classification and air flow direction. Manufacturer Glasfloss IndustriesSKU 2000450MPN GDS21211Unit Box of 12Actual Dimensions 20 5/8 x 20 5/8 x 3/4