particular handicrafts sand clock hourglass

1. It has two connected vertical glass bulbs allowing a regulated trickle of material from the top to the bottom..
2. Once the top bulb is empty,it can be inverted to being timing again.
3. Factors affecting the time include the amount of sand,the bulb size,the neck width,and the sand quality
4. It is used when an qpproximate measure suffices,as in egg timers for cooking or for board games,
5. Also good gift for home or office decoration
6. Individual handcraft,classic look,timing accurate