The easiest way to check the status of the batteries.

Features:

Quickly checks battery voltage;
Two contacts on the front for checking the 9-volt battery;
Dimensions: 10.5x4x2.5 cm.

Li-Ion 3.7V batterys:

18650, 16340, 14500, 10440, 21700

1.5V batterys:

AAA, MN2400, R03
AA, HP7, MN1500, UM3
C, HP11, MN1400, SP11, LR14, UM2
D, HP2, MN1300, SP2, R20, UM1

9V batterys:

PP3, MN1604, 6F22, 006P