... non-Ferrous metals.3. Alkaline batteries work with 10%-15% alarm rate, can work more than 40 hourscontinuously.4. Clear and ... sound, when voltage is not enough, no light or no alarm.5. Have leather cover, convenient to carry, light and good ... security inspection equipment to increase safe efficiency, such as walkthrough metal detector.-Can detect various metals, such as: Copper, Ferrous and Tin ...