Demonstrate why it is safe to stay in a car during a lightning storm. Place a discharged flask-form electroscope inside the metal cage. Bring an electrically charged rod near the cage and the electroscope's foil leaves don't move. Charge the cage by touching it with the charge rod and the foil leaves still don't budge. Why? It's a basic property of static electricity-static-electric charges can't penetrate a conductive shell. The metal cage clearly shows that electric charges remain on the outside of a conductive shell and don't affect the inside. Includes cage with metal bases and insulating stands, charging rod and instructions. Flask form electroscope is required, but not included. Cage dimensions: 26.5 cm x 11.5 cm.