Fiberglass is a plastic resin reinforced with glass fibers to produce a strong, lightweight, nonconductive alternative to metal for many manufacturing and building applications. Fiberglass angles are formed with two legs that make a 90° angle. They are strong and lightweight and are used for insulating sound and temperature in building and construction applications. Fiberglass U-channels have right-angled inside and outside corners that help them insulate temperature and sound in structural applications. Fiberglass I-beams have a good strength-to-weight ratio, resist corrosion, and are often used as supports in architectural and structural applications.