Unicel SC3-SR135 Replacement Filter Cartridge for 135 Square Foot Sta-rite T-135TX, Posi-flo Diameter: 8 11/16-inch; length: 34 1/2-inch Top end cap: open, 4-3/16-inch inner diameter; bottom end cap: open with 12 concentric slots, 4-3/16-inch inner diameter Pleat count: 195; filter media: 3-ounce reemay 2033; filter area: 135 square feet Get more efficient filtration and better water clarity with Unicel filters Longer time between cleanings; meets oem specifications