This outlet duct is for connecting the Mark 3 rear air outlet duct adapter. Specifications: Duct outer diameter: 15cm Extended Length: 2m Contracted Length: 45cm Note: 1. If you have purchased Mark 3 unit, this accessory is included. 2. When install the duct with the duct adapter, please try extending the front end of the duct and then screw it into the adapter by turning it counterclockwise. You may need to turn it more times to ensure a secure connection that won’t come loose. 3. Actual length may vary due to manufacturing tolerances. 4. Accessories of Mark 3 do not support the 30-day return policy. Tutorial video for reference