What is the inner diameter of Jetta heater water tank pipe?

The warm air box of 25 mm Jetta usually consists of water inlet pipe, water outlet pipe, water tank and warm air pipe, of which the inner diameter of warm air pipe is 25 mm. Warm air box is one of the devices that the automobile engine heats by circulating water and sends warm air into the car. It should be noted that Jetta cars may be different in different years and models, so the specific inner diameter size may be different.