2-Driver 8-inch Round Vented In-Vehicle Subwoofer Box - 50 L / 32 Hz - 761 × 344 × 344 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?