Each type of windbreaker reduces the wind only for the driver and the seat next to the driver. If you have passengers or children in the backseat its recommended not to use a windbreaker.
The HTML version of the manual (in Bulgarian) can be seen here: https://ta-chen.com/%d0%b2%d0%b5%d1%82%d1%80%d0%be%d0%b1%d1%80%d0%b0%d0%bd%d0%b8-%d0%b7%d0%b0-%d0%ba%d0%be%d0%bb%d0%b8/