Professional Digital/Knob Electric Pool Heater for Hot Tubs and Spas. High Thermal Efficiency: Boasts 460% thermal efficiency, reducing operational costs to a fraction of gas or oil boilers. Superior Heat Exchange: Features titanium heat exchanger with COP exceeding 5.0 for maximum heat transfer. Patented Defrost Technology: Ensures optimal heating performance with faster and more thorough defrosting cycles. Versatile Control Options: Available in both digital and knob control styles to suit user preferences. Eco-Friendly Operation: Operates without generating waste heat, waste water, or waste gas emissions. Enhanced Safety Design: Water and electricity are safely separated to eliminate leakage risks. Flexible Customization: Offers full customization, minor customization, and flexible options based on samples or designs.