This is your window into the device's health. In standard standby mode, it may remain blank to save power or display a "0" (if it’s a detector). If you see a number flashing, the device is communicating specific data, such as a concentration level or a weight measurement.
: Do not install behind curtains, near air vents/fans, or in high-moisture areas like directly above a sink or cooker to prevent damage or false alarms. jkd-512com user manual