Weewooday 2 Pcs Battery Meter 60 x 23 x 15 mm / 2.34 x 1.0 x 0.6 inch, Blue
$32.99
Power off what ever you are monitoring.2. Hold the button down3. While holding down the button and turn on power. The screen will display a 2 codes and let you know what it is currently set monitor.4.
