Use this Round Call Bell whenever you need to call someone's attention. Just like an old-fashioned call bell, this one can be placed on a nightstand, desktop, tabletop, or even the ledge of a bath. A gentle tap to the plunger on top is all that's needed to swing the clapper, creating a resounding, attention-getting DING No power of any sort needed so it's safe to use in any environment. Bell is small and light making it easy to carry. 3 dia, 2-3/8 high.