Small and portable: small AA AA battery tester (BT-168D), compact and lightweight, easy to carry. Test different types of batteries: the battery tester is suitable for household batteries standard and rechargeable. AA, AAA, C, D, 1.5V, 9V, Coin Cell Battery Tester. Battery-free operation: easy to read, numbers indicate power level. No battery is required. It is activated by the battery under test. Easy to read: the design of a portable device is easy to read: the battery voltage is displayed on the LCD screen.Battery Saving: You can easily test the battery voltage to determine whether the battery capacity is low or high, which prevents us from wasting a perfect battery by throwing away a good battery.