Compact, easy-to-use tester checks the condition of AA, AAA, 9V, CR-V3 and 2CR5 standard and rechargeable batteries. Just insert your battery and 5 LEDs light for a moment, indicating you've properly inserted the battery. Then 0 to 5 LEDs come on to display a charge level from less than 20% to 100%. Eliminates guesswork, assures reliable operation of cameras, flashes and other equipment.