So, when you turn the Cold Heat tool on, current flows from the negative pole of the batteries through a wire that leads to a small light. From there, it flows to the circuit board and then to the positive battery terminal. As long as solder isn't in contact with both halves of the tool's tip, that's the end of the process. Once you apply solder, the chip routes lots of power through portions of the circuit that includes the tip. The electricity moves in this way. * From the circuit board to one half of the tip * Through that half of the tip * Through the solder * Through the other half of the tip * Back to the circuit board * From the circuit board to the positive battery terminal, passing through another small light on the way The tip is as important to the tool's abilities as the circuitry. According to the Cold Heat Web site, the Cold Heat tip is made from a "patented, revolutionary composite material" called Athalite, named for "Accelerated Thermal Action." It is suspected to be made from graphite (a form of carbon) or a substance primarily composed of graphite. There are many reasons for this supposition. Here are a few of those reasons. It physically resembles graphite. Carbon has 2500 to 7500 times the resistance of copper, so it can heat up quickly when exposed to electrical current, much like this tool does. Some resistance soldering systems use graphite for thicker probes, so it would make sense that this tool would utilize some of the same techniques. The company has declined to identify the material, but it has said that it is natural and used in blast furnaces and the locomotive industry. Coal, which is mostly carbon, fits that description. Unfortunately, graphite can be brittle. One of the most common complaints in product reviews and message board posts is that the tip breaks during normal use. Unfortunately, using the recommended light pressure on the tip, it is often insufficient to complete a circuit. In order to use and enjoy this tool, you must have the knack for using just the right amount of pressure at just the right angle, completing a circuit without shorting out any electrical components being soldered or breaking the tip. If you can manage to do this, then this must might be the soldering tool for you.