The term 'deerstalker feature' refers to a type of hat that was popularized by the fictional detective Sherlock Holmes. It is characterized by having two earflaps, a VISOR, and an EARLAP. The earflaps are pieces of fabric that hang down from the sides of the hat and can be tied up or left down to protect the ears from cold weather. The VISOR is a piece of fabric that covers the forehead and eyes, and the EARLAP is a piece of fabric that covers the back of the neck. This type of hat is still popular today and is often worn for outdoor activities such as hunting and fishing.