It is part of a charging mechanism. Trigger operated, the faster you use the trigger, the more voltage is generated, the slower, the less. Almost looks like a piston. Output is around 150V max. About maybe 1/10 the size of grill starter units, but, other than size, it doesn't have a snap or hit like the grill one does, the trigger on this one operates smooth and acts as I said above. Any thoughts who might carry something like this welcome. 
