Triathlon skull caps are incredibly valuable when swimming in cold open waters, and the Zone3 Heat Tech Neoprene Swimming Cap is no exception. Wrapped in high quality 4mm Yamamoto Smoothskin neoprene with a heat-tech fleece lining to keep your head warm, while the velcro strap under the chin ensures a secure fit. Designed for year-round training and built to accommodate a variety of different head sizes.