Placing a finger tip on the glass creates an attractive spot for the energy to flow, because the conductive human body is more easily polarized than the dielectric material around the electrode providing an alternative discharge path having less resistance. The Plasma Ball is great for kids of all ages. Whether you are a fun loving work professional or a parent who wants their kids to learn about static electricity. This is a great year round gift idea. Feature - Color: Black. - Material: Glass. - Size: 29 x 14 x 5 cm. - Educational Plasma Ball: It can generate colorful streams of electricity dance across the surface, provides a great scientific learning experience for children. - Interactive Toy: Touch Sensitive: Place your finger on the glass surface and watch as colored bolts of glowing light follow your every move. - A mesmerizing static electricity display that responds to both hand touch and speaker sound, and a fascinating way to demonstrate the concepts of voltage, current, and without compromising anyone's safety. - It can activate the oxygen molecules in the air to make it easily absorbed, activate diverse body enzymes to promote metabolism and encourage better sleep. - Great gift idea to dress up your home work space or office desk. - Dear buyer, due to lighting effect, monitor's brightness, manual measurement, etc., there could be some slight differences in the color and size between the photo and the actual item. Sincerely hope that you can understand