The GA-72Cd Locator can detect the magnetic fields of iron and steel items, as well as active power lines. It generates auditory detecting signals that peak in frequency when the locator tip is held directly over the target. The GA-72Cd offers the choice of nulling or peaking. The On/Off-Sensitivity and Volume controls on both locators are designed for one-handed usage and can be found on the bottom of the cover. This allows for quick access, protects the knobs, and adds to their overall durability and dependability.