The Fisher Labs M66 Valve and Box Locator is designed specifically for finding buried or paved over valves, boxes or vaults. In addition, this model locates survey markers, water or gas meters, conduit, manholes and any other concealed metallic object. M-66 can sense manholes up to 42" deep and valve boxes up to 18" deep. The M-66 detects all metals including aluminum, brass, copper, iron, nickel, steel or tin. Combining sensitivity and accuracy with maximum ground penetration, the M-66 eliminates any guesswork when pinpointing hidden metallic objects.The electronic balance of the M-66 is easily and quickly tuned for detection within seconds while also allowing for maximum audio and visual indications. The M-66 comes ready to use.