Water storage tank with internal copper coil. 108 gallons. Disconnected from a working residential solar thermal system with 10 years of service. A comparable new tank of this size typically runs around $3,000 or more. This one is $1200 or best offer. Features an internal copper heat exchanger for closed-loop glycol systems. The glycol was maintained at proper pH for entire service life so the heat exchanger was well protected. Photos show the two original heavy-duty magnesium anode rods still very solid with some life in them still. They did the job and can do more. The factory 4,500-watt electric backup element is installed but was never used. This is a big, well-insulated tank, great for solar hot water or hydronic storage with sidearm of any type. The tank is currently on the second floor of the house, but there's easy access to a rear deck with stairs down to ground level. It's heavy, so bring a hand truck and at least two or three people to move it safely. Message if you have questions.