Armycrew High Visibility Outdoor Full Brim Hat with Back Flap Reflective Tape. 100% Polyester. Our full brim flap hat fully protects your face, head, ears, neck and back of your head from hot sun. High visibility neon color and reflective tape on the flap will make sure you are visible at all times. Breathable Mesh side panels and back flap allow ventilation which makes your head breathable, 2 small air vents on the sides. Flexible, breathable, lightweight, packable and crushable material. One size fits most with an elastic adjustable toggle drawstring in back for a secure fit.