Been meaning to do this test for a while. I used 3 machines that have VDI. Multi Kruzer, AT Pro and Gold Racer. Test was done as follows: Plastic bin 5" high with masking materials above and targets placed directly below. 3 different masks were used: 1 rust, 2 magnetite, 3 crushed coal. All 3 placed into baggies to avoid miserable cleanup after and bags were layed flat with material distributed as even as possible within the bag. All machines set at 80% gain/sensitivity. the Multi