Trampoline- Key # 2 Main Frame Rail Tube with small arc. This is one of the two components which are used for doing the primary frame of the oval trampoline. When assembling the primary frame you will need to get four of the primary key # 2 components attached together. It measures 41 1/2" extended ans it has 6 spring holes for the springs to attach into. The diameter is 1 1/2".