The Ronstan CL21 Hydrophobic Thermal Dinghy Top is UPF 50+ and is made with eco friendly bamboo fabric that is exceptionally soft and light, almost silky in its feel. With its unique microstructure, bamboo fiber apparel is highly breathable and has natural deodorizing properties. It can absorb and evaporate sweat quickly and effectively making it comfortable to wear in warmer conditions. Low collar maximizes comfort when layering. Seamless underarm panel. Waterproof outer treatment.