The cartridges are made in the USA by Aladdin, a company in business for 60 years, who makes cartridges for major pool retailers under their private label names.We buy directly from the manufacturer .... no middle man.The filter cores are made from extruded PVC pipe. The custom core configuration is designed for optimum water flow and efficient filtration. This core doesn"t require a flow restricting adapter support in the center and is the strongest in the industry. The end cap is made from high quality polyurethane to provide strength and chemical resistance, with an anti fungal Biocide added. The filter media is of the highest quality Freudenberg hydrotexx filtration media designed for the perfect balance of clarity, cleaning ability, and long life.PLEASE CHECK YOUR CARTRIDGE MEASUREMENTS FOR A MATCHReplacement Cartridge fits:Stay-Rite Posi-Flo 100Unicel UHD-SR100Pleatco PSR100,Aladdin 20201