Description Our quality Vacuum Bell Jar Demo is a great tool to discover how sound requires a medium to travel through. Remove the air from the jar and the sound from the bell gradually fades. The Demo includes a glass bell jar, vacuum base plate, gasket, hose, and battery-operated ringer electric bell. • Requires 2 AA batteries and a vacuum pump (catalog Item #6080-00 or 6076-11), not included Technical Specifications: • Vacuum Pressure for Bell Jar:
