In-Vehicle Single 8-inch Rectangular Vented Subwoofer Box - 25 L / 35 Hz - 581 × 303 × 273 mm

Can you explain the height, width, and length of the port?

Can you please explain the height, width, and length of the port? I have changed the height of the port to different numbers but the 3d rendering does not show any changes. I don't understand. When I go to view the parts, none of the dimension change. What part of the port does height and width signify?