The Tilley T4MO Hikers Hat is designed to keep your temperature regulated on long hikes. It features an evaportative inster with Hyperkewl™ technology. The Hyperkewl™ insert is activted by soaking in water, the fabric then slowly releases this water to help reduce heat stress. The broad brim of this hat helps to keep you protected from the elements and is both sun and water resistant.T4MO-1 Hikers FeaturesTemperature regulating sun hatUPF 50+ protectionWater resistantWide brimHyperkewl™ insertMesh upper for air circulationWind cord for security in windy conditionsLightweightBouyantLifetime guaranteeTilley\'s Ref.MPN: T4MO-1 Colour: Olive, Grey, Mid-Blue, Khaki/Olive and Purple HazeSizes: 56cm, 57cm, 58cm, 59cm, 60cm, 61cm, 62cmPM Ref. 972386