Oakley SI Cap Black S/MStretch fit cap with hook and loop patch and embroidery at center front Hydrolix maximizes comfort by transporting perspiration away from skin and carrying it to the outer surface where it can quickly evaporate This wicking ability helps protect the wearer from overheating in hot climates and chilling in cold climates 56 cm (S M) circumference, 16. 7 cm side panel UPC: 888896348471 Model Number: 911630 001