Horizontal screening is used in all known greenhouse designs. The principal function of this type of screening is to reduce light/heat infiltration and save energy. There are two different systems: pull/push screening and pull wire screening. The screen fabric in a pull/push system is driven via THG rack and pinion systems, which are in turn powered by a GW motor gearbox. The screen fabric in a pull wire system is driven using pull wires via a roll tube, which is in turn powered by a GW motor gearbox, the heart of the drive system. Depending on the system utilised, pull/push tubes or steel wires and drive tubes constitute the connecting components.