Unicel 6CH-940 40 SQ.FT., 8-1/4'', W/ SAE Filter CartridgeOptimal Debris Capture: Hot tub filter has sharp, uniform pleat folds that maximize water flow, minimize pressure loss, and allow full use of the pleat surface to hold more debris Filter Media: Constructed with 100 percent polyester Reemay material that balances dirt holding capacity, cleanability and durability with excellent chemical resistance properties Thread and Handle Type: Top load design includes a 1. 5 inch SAE thread and a semi circular