Headwear refers to any article of covering designed to be worn on one's head or ears. Articles of headwear are designed mainly for the purpose of providing protection from the sun, rain, wind or cold, and are also commonly used as a fashion accessory. Articles of headwear vary significantly in style and design and include, but are not limited to; hats, caps, visors, beanies and ear muffs. Headwear can be fitted or adjustable. Fitted headwear is generally manufactured in a wide range of fixed sizes to accommodate different head dimensions. Adjustable headwear, such as the case of some baseball caps, incorporates an adjustment system that allows it to accommodate different head dimensions.