American Whirlpool's Dr. Designed Zone Therapy® seats put the right size jets with the right amount of pressure at precise pain trigger points giving you the most soothing massage. The water maintenance of your hot tub is made easy with a complete 4 step cleaning system and dual sanitization. This is the same technology that is used to sanitize drinking water all over the world! This unique 3 layer thermal barrier technology reflects the radiant heat energy generated from the pumps back into the spa. This ensures that energy created by the spa stays in the spa. The Steel Sub-Structure has the highest strength to weight ratio of any building material available. Unlike wood, steel is dimensionally stable. It will not expand or contract with moisture, which over time can damage the spa’s exterior.