Unicel Pg-1903 Replacement Filter Grid for American, Pac-fab, Hayward, Astral, Waterway Diameter: not available; length: 18-inch; width: 9 3/4-inch Top end cap: not available, 0-inch inner diameter; bottom end cap: not available, 0-inch inner diameter Pleat count: not available; filter media: not available; filter area: 36 square feet Get more efficient filtration and better water clarity with Unicel filters Longer time between cleanings; meets oem specifications