A plumb bob (sometimes referred to as a plummet) is one of the oldest, most fundamental tools in surveying work, dating back to the ancient Egyptians. Even today, they are the basic tool for determining verticality with respect to gravity, used to place an instrument over an exact point in space to accurately set markers.
SECO offers a range of solid brass plumb bobs in various weights. All come with replaceable steel tips and a solid brass cap. You can even carry an extra steel tip in its convenient storage cavity.