2 Gallon Reverse Osmosis expansion storage tank with custom wall mounting brackets included. Thread 1/2" Female NPT Lead Free Applications: Domestic Portable Water Expansion Tanks are used on gas, oil, or electric, direct-fired, residential water heater and water storage tank applications to absorb the increased volume of water created by thermal expansion. It also maintains balanced pressure throughout the water supply system by keeping system pressure below the T&P relief valve setting. It is a pre-pressurized, field-adjustable steel tank with an FDA-approved rubber diaphragm, and Stainless Steel 1/2 inch Female NPT inlet connection. An expansion membrane prevents air-to-water contact in the tank ensuring a long system life. IAMPO listed and ANSI/NSF 61 certified. Wall Mountable, Custom Brackets included.