The magnetic locators are able to detect any type of metal that has a ferrous element to it. This includes iron, steel, and rebar. The devices will typically have a visible readout, as well as audio, that let you know when you’ve found a metal item. It works very similarly to a metal detector. The locator part is typically the larger part of the unit and is located at the base of a shaft. The surveyor walks around and uses the device like a metal detector to find what he or she needs.