Smiley Face Doo Rag Happy Skull Cap Mens or Womens with Bumper Sticker 100% Cotton Smiley Face, Happy Face Yellow and Black Biker Skull Cap and Buy Caps and Hats Bumper Sticker. 100 percent Cotton dries quickly and thin enough to fit under helmets and caps. One size fits many with adjustable ties. Unisex design for men, women and some teens