... series welding machine 1.CE,CCC,ISO9001 approved 2.AC-DC dual-use 3.High quality 4.Reasonable price WSE series ... gas and current.Current time control: It' s for current adjustment, and change the volume of ... is from tungsten to work piece, it's positive direction and good for removing the oxdization ... current is from work piece to tungsten, it' s negative and tungsten heats little, convenient for welding ...