The BAT-200 Battery Tester indicates the amount of charge remaining in standard and rechargeable batteries. The analog display needle moves on a color-coded, calibrated scale to quickly identify "good" (green), "low" (yellow), and "replace/recharge" (red) battery status. The BAT-200 tests 9V, AA, AAA, C, D and 1.5V Button Type batteries. Tester does not require any internal batteries to operate.