The Michael Phelps Momentum D is the largest of the range ideal for swimming and aquatic fitness. However the dual temperature means you can dial down the swimming zone to a comfortable temperature to train in but keep the hot tub area nice and hot for the hydrotherapy, and entertaining aspect. The built in Wi-Fi module allows this spa to be controlled through an app on your phone or your tablet. As with all of the Michael Phelps swim spas by Master Spas, the MP Momentum D is 153cm deep and comes with the patented Wave XP Propulsion System. Being powered by a propellor means there is no air injected into the water which makes it a more stable, wider and consistent swim with little to no turbulence along the water surface. As a result, the MP range is one of the best on the market, suitable for all swim strokes and allows for elite athlete training.