EvoShield Youth Compression Arm Sleeve Air Activated: Easty to Use - Simply rip open the foil pouch to activate the molding process. The chemical components inside the soft pads react to moisture in the air, activating the hardening process. Custom-Molding: Perfect Fit - Once activated, the soft pads transform to hard and protective, custom molding to the exact contours of each individual athlete. Ultrathin, Lightweight: Fast, Agile - At just 1/4 of an inch thin, EvoShield's protctive Shields are designed to act as a second skin with a unique protctive barrier. Athletic Design: Quick, Confident - EvoShield was developed under the direct specifications of elite athletes, ensuring a custom fit that never interferes with the body's natural movement. Breathable: Comfortable - EvoShield's protective Shields are encased within a breathable mesh layer that comfortably hugs the body.