Marey 4.2 GPM, 16L natural gas tankless water heater is a great whole house water heating solution perfect for cabins, horse stables, and mid-size homes. No electricity is required, the unit ignites with 2 D cell batteries, so it is ideal for off-the-grid areas or any other location where electricity is not available. This Natural Gas Tankless Water Heater can provide a maximum of 4.2 GPM for a perfect outdoor shower at 115°F output water temperature. output water temperature. This very versatile unit is great for many different outdoor uses such as washing your pet, washing your car, and also taking a great outdoor shower. It can also be installed indoors with proper ventilation according to local building and plumbing codes. The unit includes a convenient digital panel that allows you to adjust the water temperature and gas flow. The tankless design provides hot water on demand, saving valuable resources such as energy and water. Designed to supply up to 4 simultaneous points of use, this unit provides hot water solutions for a wide variety of applications. Its compact design saves space and is easy to install.