Product advantage: can easily indeicate power level of 9v AA AAA battery
Feature: test the power level 9V battery, the Indicator needle show the result.
How to use：
1. Directly test the 9V battery at the side of the tester, please notice the positive and negative pole.
2. Open the red part and put in the other type batteries
please notice the positive and neagative pole
Battery tester x 1