Some of the features on all millivolt heaters include the following; rust resistant water path, polymer header assembly, and a rapid heat combustion chamber. The Hayward H250 Na Ds Pool Heater is no exception. They are easy to install and maintain. Benefitting to its low profile, lightweight and CPVC plumbing capabilities. H-Series heaters are all equipped with a Cupro Nickel Heat Exchanger for efficient heating, and superior durability. The Hayward H250 Na Ds Pool Heater with Cupro Nickel provides improved durability and longevity against the damaging effects of erosion. This can occur under high water flow conditions, corrosion from occasional pool chemical imbalances, and is ideal for salt chlorinated pools. For extra protection, the Cupro Nickel material has been coupled with an improved flow rate by pass control. Together, these added technological improvements ensure that your Hayward H250 Na Ds Pool Heater outperforms and outlasts expectations.