It diffuses the jet of air, so that the hair is not blown around while it dries. The hair dries more slowly, at a cooler temperature, and with less physical disturbance. This makes it so that the hair is less likely to frizz and it gives the hair more volume. An airflow concentrator does the opposite of a diffuser. It makes the end of the blow dryer narrower and thus helps to concentrate the heat into one spot to make it dry rapidly. The comb nozzle attachment is the same as the airflow concentrator, but it ends with comb-like teeth so that the user can dry the hair using the dryer without a brush or comb. Hair dryers have been cited as an effective treatment for head lice and earwax-prevention. Types Today there are two major types of blow dryers (hair dryers): the handheld and the rigid-hood dryer. A hood dryer has a hard plastic dome that fits over a person's head to dry their hair. Hot air is blown out through tiny openings around the inside of the dome so the hair is dried evenly. Hood dryers are mainly found in hair salons. Hair dryer brush A hair dryer brush (also called "hot air brush" and "round brush hair dryer" and "hair styler") has the shape of a brush and it is used as a volumizer too. There are two types of round brush hair dryers – rotating and static. Rotating round brush hair dryers have barrels that rotate automatically while static round brush hair dryers don't. History In 1890 the first hairdryer was invented by French stylist Alexander Godefroy. His invention was a large, seated version that consisted of a bonnet that attached to the chimney pipe of a gas stove. Godefroy invented it for use in his hair salon in France, and it was not portable or handheld. It could only be used by having the person sit underneath it. Armenian American inventor Gabriel Kazanjian was the first to patent a blow dryer in the United States, in 1911. Around 1920, hair dryers began to go on the market in handheld form. This was due to innovations by National Stamping and Electricworks under the white cross brand, and later U.S. Racine Universal Motor Company and the Hamilton Beach Co., which allowed the dryer to be small enough to be held by hand. Even in the 1920s, the