Features 1、Vacuum Sound Jar: Place the electric bell in the jar, and you can hear a clear bell, and then pull out the air, the bell will gradually weaken until no sound can be heard. Close the exhaust valve, so that students can observe. The bell still keeps ringing, but no sound can be heard. 2、More Experiments: A cup of boiling hot water has been discharged into the bell jar, and then pumped, you can see that the hot water in the cup is boiling again. In addition, this instrument can also be used for experiments such as vacuum fountain, evaporation icing, vacuum coating, and atmospheric pressure. 3、Simple Operation: The operation of the sound physics demonstration is very simple, so students can have better and happier learning in class. 4、Made Of Good PVC: Adopting premium PVC material, the transparent hood can clearly demonstrate the electric bell inside, very easy to check. 5、Convenient Carry: Comes with a light weight and a compact size as well, the whole vacuum bell jar set is very convenient to carry to outdoor. Specification Item Type: Vacuum Bell Jar Material: PVC Battery: 2 x AA battery, shipped without batteries. Package List 1 x Vacuum Bell Jar 1 x Bell 1 x Vacuuming Plate