Hi-Start might actually put your sailplanes or RC planes into the air.
These are 10 meters UNSPLICED tubes of rubber. They make the best possible "Hi-Starts" for RC sailplanes because they can be stretched 5 to 7 times their own length. The tubes are colored not only for better visibility when they are laying on the ground, but also because the color dies give the rubber protection from ultraviolet radiation and ozone.
In addition to the color dies the tubing also has a small amount of a microcrystaline wax in it. This wax migrates to the surface of the tubing appearing as a whitish dust. The purpose of this wax is to provide further protection against ultraviolet rays. When not in use these Hi-Starts should be stored in a brown paper bag or box. A waxed bag or box is even better. Storing them this way should ensure years of excellent performance from your Hi-Starts. Silicon rubber Bungee Cord stretches to 6 times its original length and is light weight giving a consistant pull, great for gliders and EDF jets of up to 3kg.
Features: Brand NEW red Length: 10m Outside diameter: 6mm Inside diameter: 4mm Design for gliders or Rc planes up to 3 KG.
See bungee cord working on youtube https://youtu.be/jvBcq18jkk8?t=36s