Developed primarily as a layer for blocking UV rays, the Arm Foil also adds a touch of warmth in cool weather. Constructed with our Circular Seamless technology, the Foil fabric is free of any irritating side seams, creating a uniform tubular knit that's ultrasoft against the skin. The top and bottom sections feature a smooth band to securely hold the sleeves in place. _x000D_ _x000D_ The Foil yarns are made of polyamide and elastane that transport and evaporate moisture much quicker than traditional polyester blends, resulting in a breathable first layer that keeps your arms protected.