The mesh helps to both ventilate warm air out & allow cooler air to flow in while the sturdy cotton fabric is rugged yet exceptionally lightweight. Tilley T5MO Organic Cotton Airflo Hat
Features: Guaranteed for life not to wear out Insured against loss Excellent sun protection, rated UPF 50+ Dark underbrim for glare protection Repels rain, floats Ties on in the wind Machine washable, wont shrink 4-page Owners Manual Secret pocket Medium brim with ¾ ventilation mesh Made from 98% organic cotton & 2% Spandex. Mesh made from 100% polyester. The fabrics of all Tilley Hats have been certified to block 98 percent of harmful UVA/UVB radiation & deliver an ultraviolet factor (UPF) of 50+, the maximum rating given.