The rear door glass window can be either fixed or be raised and lowered by depressing a button (power window) or switch or using a hand turned crank. The door glass is appropriate for safety and protection of debris in the road and also car theft. It also comforts the driver as well.
Certain retracting windows were operated by direct (up or down) pressure, and were held in the up position by friction instead of by an internal lift mechanism. Other vehicles have hinged windows with a folded lever mechanism to push and hold the window out from its closed position. The provide protection and security to the vehicle and passenger inside.
Glass will be inspected for cracks or damage before shipping