Prokit's Industries MT-4018 - Manual (Page 9)

5. Continuous working mode
When you need to measure sound continuously,
should cancel automatic shutdown function. To get
that, before meter starts working, press button
Down
and button ON/OFF at the same time,
automatic shutdown will not occur.
6. Low voltage indication
When battery voltage is too low to work, a battery
symbol appears on screen. It reminds you to
change battery.
■. Keys instruction
1. ON/OFF
key
Press the key to turn the power ON. When meter is
working and stop to press button for two minutes,
shutdown will occurs automatically.
2. AUTO/MANU
key
Press AUTO/MANU key to shift auto or manual
measurement mode.