This is a 1.66 pound spool of 46 gauge, heavy build MW-80 copper magnet wire. The enamel coating is red in color, and the wire has an overall diameter of 0.0020". In general, magnet wire allows multiple layers of wire to be wound together without short circuiting. As such, it is useful in a variety of applications including electromagnets, transformers, Tesla coils, speakers, inductors, guitar pickups, and motors.