Compare feature-to-feature with any other electric spa heater and you'll see why SpaPak sets the standard for performance. All waterways are corrosion-free copper or bronze, not aluminum, which will provide longer, more dependable heater life. The SpaPak features a large size, heavy-duty incoloy heating element that far outcasts ordinary water heating elements. The SpaPak is easy to install with a compact design that fits into small spaces. Full flow 1½ inch, MIP inlet and outlet connections are conveniently located. Both models are 240 volts, have a width of 9-1/8 inches and a depth of 5-3/4 inches.