8 outlets allow you to adjust the airflow for 8 aquariums Inlet connector diameter: 10mm and outlet diameter 8 is 5mm. Manually control the flow of vital oxygen or turn an air pump on or off. Made of chrome-plated copper, the air never escapes. Not suitable for CO2 system. Weighs 0.2 kg, measures 16 x 6 x 0.5 cm.