SwimEx is the only resistance pool preferred by home owners, professional / college athletic teams, and physical therapy centers worldwide. The owners of this 500 S swim for fitness but also just relax in this swim spa room almost everyday. The kids love it also! The 500 S model utilizes “side channels” as a water return system enabling a greater water depth and faster counter-current pool water speeds. These side channels include 2 built in seats on each side to allow for total relaxation.