For use in conjunction with a Walk Trough Metal Detector, or stand alone, a Garrett Hand-Held detector is a good choice.
Garret handheld metal detectors are characterized by their great sensitivity and reliability. It is not without reason that Garrett handheld metal detectors are used by the Royal Netherlands Marechaussee at Schiphol. Garrett handheld metal detectors are often imitated, but they have never been equalled!