Thick diaphragm keeps water separate from pre-charged air and helps to reduce air loss NSF certified. Molded diaphragm offers an ideal fit sits on top of the water and will not fold crease or drag against the steel shell. Polypropylene-lined steel supports water weight to ensure water never sits in loose-fitting vinyl or rubber bags that can fold crease and wear NSF certified. The Polypropylene liner separates water from the steel shell to prevent taste or odor from being absorbed into the water. Formed liner fits the steel shell for added durability. Sizing-count the number of water fixtures inoutside the home multiply that by 3 there are no disadvantages to having a larger tank fewer pump cycles will extend pump life and save money on electricity. Stainless-steel waterway lining has no plastic to cross-thread strip or crack. Pre-charged to 38 PSIG 100 PSIG maximum working pressure – maintains air charge for years to provide easy upkeep. 1in NPTF connection offers easy installation uses malleable iron for dependability. Made in the USA.Easy installationMaximum 100 psi pressure rating for residential useHeavy-duty diaphragm is designed for extended lifeLocking ring provides an airtight diaphragm seal for years of dependable serviceHigh-grade polypropylene liner is non-metallic for clean. fresh. great tasting drinking waterWeather-resistant paint system withstands damp environments without corrodingDurable steel base provides strong support