DeSoto Shield Del Sol Arm Coolers Another De Soto Original. We invented this sleeve which is worn on hot days to keep you cool and protect you from the sun. Shield Del Sol Skin Cooler Stretch fabric block 90% UVB rays, breathable, cooling, silicone gripper elastic on upper arms. Skin Cooler SDS (Shield Del Sol) Blocks 90% of UVB rays - When the human body gets hot, it sweats to cool itself. In the past, other brands have tried to help that process by developing fabrics that wick moisture away from the skin and expedite evaporation. For over 10 years now, De Soto has taken this concept a step further by using that moisture to create a cooling effect. YES! WE WANT YOU WET. Skin Cooler works by a series of channels knitted into light fabric. As these channels get wet, they absorb moisture and swell, which dissipates the heat making the fabric against your skin actually cooler. How much cooler depends on factors including airflow, humidity, ambient temperature, and moisture temperature. When you sweat, the garments temperature drops and creates an actual cooling sensation. Skin Cooler SDS offers this cooling effect while offering even more sun protection.