Zilmet has over 50 years of experience in manufacturing high quality diaphragm well tanks. Each tank is factory leaked tested to ensure tank integrity. Made with certified synthetic SBR rubber diaphragm, with all diaphragms designed to maximize drawdown. MIG welding eliminates interior rough spots and sharp edges. Welded side outlet allows easy and quick installation. Low profile tank design with full membrane depth eliminates stretching of diaphragm, providing increased life cycle. External baked on epoxy-polyester coating provides durables appliance like finish. Protected pre-charge valve eliminates potential leak path. 5 year warranty on all models. Carbon Steel Shell, with Stainless Steel Connections. All models are gray colored. 60 psi Max working pressure for 2.1 gallon-13.2 gallon models. Max operating temperature 210° Farenheit. Factory pre-charge of 12 psi.