The Manual Sidewall Lift Crank rolls up the sides of the greenhouse to provide ventilation and access. In order to install sidewall ventilation systems, we recommend using the Jiggly Greenhouse® Snap-On Clamps and the Steel EMT Coupling. Proper ventilation in a greenhouse or any outside enclosure is vital for a healthy, crop-yielding operation; these economical products will help you grow the best possible crops for a minimal cost.