DESC: Enjoy the soothing effects of powerful, invigorating bubbles in your spa without excess equipment noise Thermally protected blower motor shuts off automatically under excessive operation temperatures for protection against motor damage. Restarts automatically after cooling. Unique thermal relief valve reduces nuisance tripping due to temporarily blocked or restricted jets and provides longer uninterrupted service Built-in check valve adds protection against blower damage from water surges UL listed for both indoor and outdoor use, Manufacturer: Polaris