Water Worker Water Heater Expansion Tank Diaphragm-type pre-pressurized expansion tank specifically designed for potable hot water systems. These tanks control water pressure build-up and eliminate relief valve spillage caused by thermal expansion when water is heated. 3/4 Male pipe thread connection. Requires no maintenance. Required by code in many counties and states. Use model Capacity 4.4 Gal., Pressure Rating 150 psi, Dimensions 15 In. H x 11-1/2 In. Dia., Connection Size 3/4 In. MIP, Material Steel, Pkg Qty 1, Package Type Box Warning This product can expose you to chemicals including lead which are known to the State of California to cause birth defects or other reproductive harm. Fo more information go to www.P65Warnings.ca.gov