Small and portable: small AA battery tester (BT-168D), compact and lightweight, easy to carry. Test different types of batteries: The battery tester is suitable for standard and rechargeable household batteries.AA, AAA, C, D, 1.5V, 9V, button cell battery tester. Works without batteries: easy to read, numbers indicate power level.No batteries are needed.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.