This demonstration barometer is used for measuring air pressure and demonstrating how an aneroid barometer operates.  

Encased in a transparent acrylic case which allows full view of the movement.  The barometer responds to changes in the air pressure.  The action can be demonstrated with the help of a rubber bellow which increases the pressure when squeezed. Supplied complete with rubber bellow.
Size:  100mm dial  
Graduated:  28 to 31 inch of mercury
960 to 1060 millibars