... :1Screw :1display : 1Method of every buttonThere is a button below which is very important.,it is used frequently ... , In the "critical sound" before, must press a button, and the good then loosen button. If in ... detecting,keep 10-15cm move above ground,don't distance a lot ,or will affect the depth you ... non-ferrous metals to make the sound increase, a large black metal to make the sound decreased; ...