Items that can check the remaining amount of the so-called 9V battery. Because it is compact, the case pocket is unloaded, and it is suitable for checking the battery remaining capacity of the actual base and effector. It is easy to use because it can be used just by fitting.
From the following maker site
006P Level checker for type dry cell (9V battery).
The body weight is about 9 grams and lightweight, and can be placed in the case of the case of the instrument case, and the battery remaining can be measured when needed. For the remaining amount of battery, active guitar, active base, and effector.
The display is digital display and displays the battery voltage. (If "9.00" is displayed 9 V.)
The color of the LED panel is two colors of Blue and Green.
Outside size: Width (W) 32 mm, depth (d) 21 mm, height (h) 20 mm
Consumption Current: 18mA or less
Weight: about 9g