The T5MO Organic Airflo Tilley Hat, designed with a medium brim, is made of a soft, suede certified organic cotton with polyester mesh and a Hydrofil sweatband. If you are looking for maximum ventilation, then the 3/4" mesh around the crown of this hat gives you just that. Couple that with the lightweight and naturally breathable fabric, you will hardly feel like you have a hat on at all! As well as performing great in warm weather, this hat has some great features for extra protection in the wind and rain too. The fabric has a water repellent finish to keep that rain off and the front and back cord system will help keep your hat where it should be when the wind gets up. The mesh helps to both ventilate warm air out and allow cooler air to flow in while the sturdy cotton fabric is rugged yet exceptionally lightweight. All this makes for a hat which is excellent for all activities. Tilley T5MO Organic Airflo Hat - Khaki