Wear the Rover and your feet will be tuned to the Swellular Technology of superior comfort, support, and traction.. . . . . Swellular technology provides outstanding comfort, support, and traction. Supersoft contoured foam footbed delivers instant comfort. Medium density molded foam midsole gives long lasting support. High density sawtooth rubber outsole provides superior traction, protection, and durability. Water friendly synthetic nubuck upper. Textile liner with extra padding for soft comfort against the foot .