Hammocks made of Breathable Performance Ventaleen™ Technology are water resistant, elastic, breathable, UV resistant, cooling, & strong. Ventaleen™ Technology is a loosely, micro-woven polyester fabric, which allows more airflow between you and the hammock bed; giving it a cooling effect. Its woven pattern makes it behave like an elastic fabric; it has more give for added comfort and strength. Ventaleen™ Technology is specially coated with water-resistant and UV-resistant agents, allowing it to last longer and dry faster than traditional cotton or polyester fabrics.