The Zenair uses a "bungee" cord style of landing gear. These elastic cords are very strong and almost impossible to stretch by hand. The device shown in the photo is used to hold the cords in place so that the landing gear can be installed.

The custom-made "wrench" was simply made from a piece of scrap one-eighth inch thick piece of aluminum. It is used to turn the wing nuts on the landing gear installer when they get too tight to turn by hand.