This a professional underground metal detector with LCD
It has three tones to indicate different metals
It is a good choice for main order company
MD-3020II hobby metal detector:

• Three operation modes: all metal, disc, notch
• LCD displays the type and depth of the target
• Sensitivity: >15cm (for the US quarter)
• Low battery indication
• Three tones to indicate different types of metal
• Frequency: approx 6.6kHz
• Variable S-rod shaft length and arm support handle for convenient and comfortable use
• 8" waterproof search coil
• Two 9V batteries required

Gold range

• Iron foil: indicates that the target is probably iron or foil, some oxidized iron might register somewhere within the silver range
• 5￠ (nickel): indicates that the target is probably 5￠ or a nickel, some small gold rings might register within this range
• Pull tab: indicates that the target is probably a pull tab of an aluminum can, some small gold rings might register within this range, might register within pull tab category
• S-caps: indicates that the target is probably a type of metal like bottle cap with whorl, some medium sized gold rings might register within this category
• 1￠: indicates that the target might be a zinc penny or a copper coin, some large rough gold items might register within 1￠ category