Cartridge Check Valve System Kit Back Catalog number: CTS-21011 Manufacturer: SCIENCIX Availability: In the manufacturer's stock Price on request - + Recommended 11-2525 1/4" Short Comp. Screw (Gold-Plated), 10/pk Price on request CTS-21089 Needle Seal (For pH 1-14, for operation up to 130 Price on request 11-3321 Wash Seal Gasket, 6/pk Price on request