Hair clipper guards, or combs as they are sometimes called, are the attachments that determine the length of hair left after a haircut. They fit onto the blades of electric hair clippers to control how close the blades come to the scalp or skin. For example, a "number 2" guard will leave hair about 1/4 inch long, while a "number 8" guard will leave hair about 1 inch long.
Hair clipper guards are essential for barbers and hairstylists, as they allow them to create a variety of hairstyles with precision. They are also popular for home use, as they make it easy to trim hair at home without having to worry about cutting it too short. One of the key developments in the history of hair clipper guards was the invention of the adjustable guard in the early 20th century. This allowed barbers and hairstylists to easily adjust the length of the guard without having to change attachments.