Eemax AutoBooster essentially gives a 50-gallon tank the same capacity as an 80-gallon tank without the need to upgrade. (it’s an affordable one-time installation that leads to cheaper energy bills for years to come).
Installed on an electrical hot water tank it also helps to save energy (as homeowners can switch off power when they’re away) and money.

How does AutoBooster work? The Eemax AutoBooster installs directly onto the hot water outlet of a tank. AutoBooster senses the temperature of the tank’s outlet and starts heating when the tank’s outlet temperature drops below the AutoBooster’s set activation point.

How will AutoBooster improve your water heating system? AutoBooster adds efficiency in a variety of ways. A combination of higher tank capacity, better water quality and lower energy use, more consistent water temperature at the shower head, all contribute to a better overall water heating experience.
You don't heat up extra water in a tank where it will just cool down when not needed and have to be reheated.

Rheem 50 gal gas hot water heater $500-$700
Rheem 75 gal gas hot water heater $1,000
Eemax AutoBooster $450-$500