One size fits most, Hunter Skipper black and white FLEXFIT trucker hat.  Great for outdoors as well as casual wear.

55% polyester, 43% cotton, 2% spandex; 6-panel, structured, low-profile; eight-row stitching on bill; hard buckram backed front panels; polyester/spandex mesh on side and back; spandex sweatband retains shape; Silver underbill;