Lightweight materials contribute to the overall efficiency of the 757 models. Improved aluminum alloys, primarily in the wing skins, save 610 pounds (276 kilograms). Advanced composites such as graphite/epoxy are used in control surfaces (including rudder, elevators and ailerons), aerodynamic fairings, engine cowlings and landing gear doors for a weight savings of 1,100 pounds (500 kilograms). Another 650 pounds (295 kilograms) of weight savings is attributable to carbon brakes, which have the added advantage of longer service life than conventional steel brakes.