Features:

1. Electric bell uses two AA batteries (3V DC).
2. Glass jar for covering the base, approximately 19 cm in diameter and 24 cm in height.
3. Rubber pad between the glass jar and the base to prevent air leaks.
4. Circular base, approximately 20 cm in diameter and 3.5 cm in height, with a valve for connecting to a vacuum pump.
5. Rubber hose for connecting the base to the vacuum pump.
6. Operating temperature range: -10 to 40 °C, relative humidity up to 85%.
7. For use with a vacuum pump and two AA batteries.