Magnetic Reed Switches are used for a variety of electronic applications, including magic tricks,  where you want an item to turn on or become activated when brought into a magnetic field, or when a magnet is brought near the electronic item. Each measures approx. 1-5/8 inches long and are extremely sensative.

To use, simply solder into the wiring, between the battery/power source, and the primary object (light bulb, motor, etc). No instructions. Soldering equipment or solder glue are required to utilize.