Ultralight and packable, this broad sun hat offers an oasis of shade. Great for hiking, kayaking, canoeing, and general summer wear. . SolarShield fabric provides UPF 50+ sun protection. 86% nylon, 14% polyester. 2.5 inch brim. Foam-stiffened brim floats (a nice feature for boaters). Coolmax mesh headband moves moisture away from while your brow. External drawcord adjustment in headband keeps it snug on long trails. Removable chin cord with cordlock. Sizing: Measure from center of forehead around fullest part of head. Medium: 22.5 in./57cm, Large: 23.25 in./59cm.