mfr: SIMMONS MFG CO Used in jet pump water systems. Maintains proper charge in conventional tanks. Prolongs pump life by reducing frequency of cycling. No. AV-45: Part No. 15770, 80 Maximum Tank Gallons, 1/4" FIP. No. AV-100: Part No. 15770, 120 Maximum Tank Gallons, 3/8" FIP. No. 15679: Part No. 15679, 42 Maximum Tank Gallons, 1/4" FIP. This item cannot be shipped to APO/FPO addresses. THIS ITEM CANNOT BE RETURNED. Please accept our apologies