Dimensions: 11" x 24" - 48 sqft. American, Hayward, Pac-Fab, Sta-Rite, Jandy, Vertical DE Grid (7 required) Unicel Vertical grids are constructed for use in Diatomaceous Earth (DE) filters and have a reinforced center core for added durability. They are covered with mildew and rot resistant polypropylene cloth. The seams are stitched with chemical resistant heavy-duty string and sonic welded to prevent fraying.