Features on all millivolt pool heaters include, pilot ignition system, rust-resistant water and a rapid-heat combustion chamber. It requires no external power supply for  pool heater operation.
To be added to detail page with the short description:  
Key Features:

• Rust resistant water path
• Rapid heat combustion chamber
• No external power required
• Not intended for high wind areas

Piloted ignition systems are not available for installation in all parts of the United States.  For help with selecting the proper Hayward heating product, consult local pool professional.