This is a pen with a special ink that when dry, will conduct electricity. Meaning you can literally draw some basic circuits on a piece of cardboard and they’ll work. Connect them to some resistors, or LEDs or whatever else elements go into a circuit and teach yourself or a young one the fundamentals. The surface resistivity is 55 ?/Sq @ 50 microns, if that has any meaning to you, and you should probably not use it with voltages above 12V. It’ll work on just about any surface except skin, and maybe metal and will set you back all of $12 or $19 for two.