The AIRKUHL(TM) Cap is cut from an ultralight, quick-drying, and cooling nylon with perforated laser-cut venting. Technical construction eliminates added layers, and a foam-free ICEKUHL sweatband reduces your skin temperature. A reflective, easily adjustable elastic backstrap creates the perfect fit and keeps you visible while UPF 50+ protects you from burning rays. This is the ultimate tech running cap for those who are relentless about the pursuit of excellence on the road less traveled. Sizing S/M circumference is 54cm L/XL circumference is 58 cm Ultralight with laser-cut perforations for unmatched breathability and comfort ICEKUHL(TM) sweatband with innovative cooling technology to reduce skin temperature Sweatband designed without heat-retaining foams to help keep you cool and comfortable Glued and taped seams are lower profile than traditional stitching and binding Flexible and floatable EVA foam brim retains its shape when packed UPF 50+ provides maximum UV protection to covered areas Reflective backstrap for visibility at night Nylon and Spandex