The self propelled pallet wrap robot has two different pre-stretch ratio for switching. This video demonstrates how the switch is made in simple actions.>>>by pressing the buttons upside the plastic gear, you can easy to press it down or raise it up. The ratio is changed as the gears are rematched. From our experience, the higher ratio is preferred when using high quality stretch film, which will save more in consumption and make tighter wrapping. The lower ratio is preferred when the stretch film is cheap and poor, lower pre-stretch ratio will decrease the chance of film break.