The Max-E-Therm pool and spa heater by Sta-Rite, also known as Pentair, is a high performance heater. It's ideal for retro-fit installations. It is a lightweight, compact heater with best in class energy efficiency. It's features include an LED temperature readout with dual thermostat controls, temperature safety lockout, and a 6-position control panel. It is made of Dura-Glas, which is an exclusive Sta-Rite material. The material is able to handle the heat, weather the elements, and handle harsh applications. The Max-E-Therm® is environmentally friendly - featuring low NOx units. It also helps reduce operating costs; it has an 84% efficiency rating. Feel free to contact the pros at PoguePoolSpa.com for more information.