Tig holder holds your filler rod and lets you advance the filler wire by thumb wheel .Tig finger feeder feeds tig filler rod comfortably. Hold the feeder like a pen or pencil. Insert the tig filler wire from the rear of the unit – not from the front. With the feeder comfortable in your hand, advance the wire by rolling the rubber wheel with the tip of your index finger. Suitable for tig wire diameters 0.8mm (.030”) to 3.2mm (1/8”).