HO Sports RAD 4 4 Diameter inflated The Round Aquatic Devices RADs allow anyone, regardless of skill level, to participate in a day behind the boat. The riding possibilities are endless. Fun for all ages, the RAD is guaranteed to turn some heads on your lake this summer. Drop Stitch is the material HO is using to create the RADs and FAD. This material allows them to build inflatable items that can be inflated to optimum rigidity while delivering the most durable inflatables theyve ever offered.