While the detector is shielded above, below and on the sides, metal objects have to be kept from the entrance and exit of the detector opening as shown below. No metal can be located in this area. Large moving metal should be kept fifty (50) percent further away or at least two (2) times the smaller aperture dimension. There are special models available for operation in areas which require smaller metal free areas.
For further information on how to correctly install your medal detector check out our Goring Kerr Manuals for purchase.
Metal Free Area