The measurements should be taken up to mm (including the rubber sealing), both ways - in width and in height. Subtract 4 mm from the width. This is the final width that you should specify in your order request. In some cases, however, the window might be curved. Therefore, it is recommended to measure the width of the window at both ends (upper and lower) and in the middle. If there is a difference in the width, please take the shortest one. Measure the height at both ends (left and right) of the window and take the longer one (in case there is a difference). This is the final height that you should specify in your order request.