Use this to refill your air tanks. It must be set up correctly in order to function properly The Water Electrolyzer MUST be placed ON TOP of a furnace. The W.E uses the heat of a burning furnace to separate water into Oxygen Gas and Hydrogen Gas. The Hydrogen Gas is lost in this inefficient model. Water buckets go in the left slot. Air tanks go in the middle slot. (Any air tank of any fullness will accept more air EXCEPT a 100% full Air Tank) Each Bucket of Water will add 5 minutes of air into the tank. Remember, the furnace underneath must be burning fuel in order for the W.E to fill tanks.