First of all, I know nothing about this item. I got it and I want to sell it. It looks brand new, but it might have a missing piece, I am not sure. If you buy it and it is missing a piece, I'm sorry but you can't return it. You're welcome to check it out when you come to buy before you buy. This is the description of the item on Amazon. Polyester Filter Cartridge: The high-density polyester filter cartridge with 14 m³/h maximum water flow, not easily deformed and convenient to backwash for reuse, can absorb grease, filter dust, block leaves, and hairs, and eliminate odors effectively. Note: Regular cleaning can extend the cartridge’s service life. Durable Filter Housing: The filter housing is made of glass fiber polypropylene material, injection-molded, durable, and corrosion-proof for long service life. At the same time, the ring lock design of the cover can spare the troubles of screws, and you can open the cap and replace the filter element easily. In addition, the imported O-ring can ensure good airtightness. Auto Pressure Relief Device: The pool filter is equipped with a high-precision pressure gauge, allowing you to know the pressure in the filter at all times. The user-friendly automatic pressure relief valve empties the air trapped in the filter automatically to prevent excessive pressure. Easy Installation: The swimming pool filter has two water inlets and a water outlet, including 2 unions for easy installation. One of the water inlets can be plugged with the plug, the other water inlet can be connected to the pump, and the water outlet to the swimming pool for water purification. Wide Application: The pool cartridge filter has a wide range of uses. It is suitable for water purification of in-ground swimming pools and above-ground swimming pools, even inflatable swimming pools. There is no doubt that the pool filter will bring you and your family a clean, refreshing, and pleasant summer.