Source - Waterdeep: Dungeon of the Mad Mage

Wondrous Item, common

This common wondrous item is a hollow, 5-inch-diameter orb that weighs 5 pounds. Its outer shell is composed of notched bronze rings, which can be turned so that the notches line up. Aligning the notches requires an action, and doing so causes the orb to gong loudly until the notches are no longer aligned. The sounds are spaced 6 seconds apart and can be heard out to range of 600 feet.