The Rheem Electric Spa Heater has a completely non-ferrous waterway. The cast brass headers are connected with an all copper water tank. This ensures that the spa water only comes in contact with a rust free environment. This helps keeps your spa rust stain free. The heart of any electric heater is the heating element. The Rheem Electric Spa heater comes with a robust, incoloy sheathed heating element. Every Rheem electric spa heater comes standard with 1-1/2" NPT male connections to make your installation secure and effortless. No other special connections are required, such as current collectors or heat sinks.