Hayward W3H400FDN Universal H-Series, Low NOx, 400,000 BTU, Natural Gas, Pool and Spa 
"Totally Managed" Flow saving energy by reducing pump run time
Silicon Nitride Ignition System
Cupro-Nickel Heat Exchanger ensures compatibility with almost all pool systems including salt pools
Low NOx certification
83-84% industry-leading thermal efficiency
Patented header by-pass design
Corrosion resistance
Digital LED display
High and low voltage options (110V or 220V)
3/4" Gas Connection at heater
delivery available / installation and removal of old heater available