Lifegard Replacement filter pad material is bonded to keep its original shape. It has superior filtration with uniform and consistent material and filters all size of particulate matter. Instructions: Make a pattern out of cardboard or paper to match the size of your filter box opening. Place a pattern on the filter pad material and cut 1/4" larger on all sides for a snug fit. Insert pad into filter Blue side up. For even better filtration, cut 2 pads and sandwich a bed of Lifegard Activated Carbon between the 2 pads. Available Sizes: - 15 inch. x 2 feet - 15 feet x 2 feet