MetalliScanner M40 detects metal in wood, drywall, paneling, tile, stucco, plaster, concrete, and other nonmetallic surfaces. It locates ferrous (magnetic) metal up to 4 inches (102 mm) deep and nonferrous (nonmagnetic) metal up to 2 inches (51 mm) deep.

MetalliScanner finds studs in lath and plaster walls. It works by finding the pattern of nails that attach the wood lath to the studs. MetalliScanner M40 finds plumbing, ductwork, rebar, nails, and screws in your walls, floors, and ceilings, and is great for scanning reclaimed lumber for hidden metal.

MetalliScanner M40 has two scanning positions, each with a progressive LED display. As it approaches a metal object, the red LEDs progressively light from the bottom up. The top lighted blue coil and an audio tone indicate when a metal target is located.

Use Pinpoint Scan to locate small metal objects such as screws and nails
Use Wide Scan to detect metal in walls or concrete
LED arrays indicate signal strength

We have more tips in our home improvement book http://www.amazon.com/dp/B01BK2K0JM?r...