To protect you from the sun and rain, Tilleys fit lower than other hats. For your comfort, they're held on by gravity, not painful pressure on your forehead. On a hot muggy day, you'll especially appreciate this! Even though they fit gently, Tilleys won't fly off because when there's a breeze, you use one or both parts of the tuckaway Wind Cord. THEY FLOAT! A layer of closed-cell foam in the crown provides the Tilley's positive buoyancy. The Tilley comes with a tuckaway, adjustable, fore 'n aft Wind Cord. When it's calm, the Wind Cord stays hidden in the crown. When there's a breeze, place the part with the sliding knots behind your head. When it's windy or you're sailing, use the chin part too. It's also preshrunk. Soft and comfortable, it picks up sweat from your forehead and wicks it away to your temple area where it evaporates. The fabric and style of all Tilley Hats have been certified to block 98% of harmful UVA/UVB radiation and deliver an ultraviolet factor (UPF) of 50+, the maximum rating given.