Waterproof Men's Wide Brim Sun Hat. Polyester. Great for out sports. UV Protection, Wide Brim Bob, Panama Hat. A sun hat (also known as the harvest hat or field hat is a head covering specifically designed to shade the face and shoulders from the sun. In modern times, sun hats are common in places around the world, mainly in holiday resorts residing in countries close to the Earth's equator. They are particularly useful in protecting against ultraviolet rays (UV). The style of a sun hat can range from small to large brims. However, as a general guideline, the brim is four to seven inches in width. Size: 54-59cm (21.3-23.2 inch). Delivery: 14-24 days.