The Rheem RTEX tankless has external adjustable digital thermostatic control with LED display (+/1 degree accuracy. Designed with durable Copper immersion two heating elements, field Serviceable.Self-modulating power control. It offers simple installation – 1/2 NPT adapters included; side 1/2 inch Compression water connections. The best part of the Rheen RTEX 13 s that it is 99.8% energy efficient. Rheem Rtex 13