 Specialized bungees, such as some used in bungee jumping, may be made entirely of elastic strands.Bungee cords have been used to provide a lightweight suspension for aircraft undercarriages from before World War I, and are still used on many small homebuilt aircraft where weight remains critical.Bungee cords were also used in parachuting to assist in opening the old-style parachute container after the ripcord was pulled.