A plumb-bob or a plummet is a weight with a pointed tip on the bottom that is suspended from a string and used as a vertical reference line.
This instrument has been used since the time of the ancient Egyptians by bricklayers, masons, and carpenters to ensure that their constructions are "plumb", or perfectly upright.
We realize chances are you will never tote around something around as low tech as string and a weight so PlumBob is here to help you make sure your wall are straight in your house.
砌砖工，石匠，木匠用的铅锤工具，帮你确定垂直