Patent-pending Alpha Technology. Rubber-clad neoprene for ultra lightweight comfort with 100% waterproof protection. 3mm neoprene provides stretch and conformed fit. Sport Chassis outsole system cradles the foot for all-day walking comfort. Webbing pull-tabs for easy on. EVA footbed for added comfort. Internal foam and rubber for cushioning comfort. Aqua tread beveled-lug outsole prevents debris build-up.