The anode is connected to hydrogen, and the cathode is connected to the air in the atmosphere There are 2 air inlets/outlets atthe negative electrode of the cell,the upper is air inlet and the lower is air outlet High quality for professional use A wonderful replacement for broken or old one, ensures long and better work performance No short-circuit operation, no external voltage across the cell voltage, Weight: 0.13117504589 pounds, Manufacturer: Htuteyy