The Natural Form (Refresh & Euro) Series are our newest and most innovative technology. With up to 40 air springs per sleeper our mattress creates a 40 to 1 ratio compared to the industry standard. Creating the most responsive air mattress on the market, it conforms naturally through our patented technology. So no pumps, sensors, or electricity is used! This series comes with Free delivery, a 10 year warranty, and our 100 night sleep trial.