Identifying Small Glass Tubes Containing Three Tiny Ball Bearings: What Could They Be?

freely when the tube is tilted?

Is the tube mounted inside a larger object?

Are there markings, arrows, or position indicators?

Does the tube have metal fittings at either end?

If the balls move in response to changes in position, the object may be part of an indicator or demonstration mechanism.
2. A Scientific or Educational Demonstration Object

Small glass tubes are common in laboratory equipment, teaching demonstrations, and science-related novelty items.

A tube containing metal spheres might be used to demonstrate movement, friction, gravity, or another physical principle.

Clues to look for:

Is the tube made from clear laboratory-style