The Sharkskin Performance Wear Long Sleeve top uses chillproof material to keep your torso and rear kidney area protected with a breathable compression fabric in the shoulders and arms to aid in endurance and muscle recovery. The compression fabric is SPF50+, providing protection for your arms and shoulders from the sun with a heavy-duty zipper to control heat retention and mesh panels for ventilation to allow for maximum performance as weather conditions change or as your heart rate climbs.