The instrument has been used since the time of the ancient Egyptians by bricklayers, masons, and carpenters to make sure that their constructions are perfectly upright.
A plumb-bob or a plummet is a weight, normally has a pointed tip, its supposed to be suspended from a string and used as a vertical reference line, or plumb-line. Finally you have a digital version of a Plumb, if you normally need one.. then this is the perfect tool for you,