Porcelain-lined, steel water heaters feature an anode rod to "absorb" the electrolytic action, ensuring that your water heater lasts longer. With the fastest recovery in the industry of 7.6 gallons per hour. Copolymer insulation jackets specially fit the tank to retain heat. Easy to install, operate and maintain. Four gallon features 9,000 BTUs and is 12-11/16"H x 12-11/16"W x 16-1/8”D. Cutout size: 12-3/4"H x 12-3/4"W. Access doors sold separately. 1 per box.