10 gallon water heaters provide the equivalent of 16 gallons of hot water and the six gallon yields 9 gallons. Features pre-installed winterizing by-pass kit. 10 gallon cut-out: 15-1/2 inches H x 16 inches W x 20-3/4 inches D. 6 gallon cut-out: 12-1/2 inches H x 16-1/2 inches W x 18 inches D. Durable, powder-coated access doors are included. 2 Year warranty. 1/box.