The Green Light corresponds to the sensor that measures the Heartbeat and the Red Light that measures the Oxygenation of the Blood.

Flashing green sensor:

1. When a health measurement is performed manually.
2. When the Watch performs automatic health measurements every hour.

Solid Green Sensor:

1. When the 24h monitoring function is active in the device.

 The Watch Generation 2 has a red sensor that functions with measuring the level of Blood Oxygenation.

The red sensor is located on the side of the Watch Generation 2, and it is activated when the Blood Oxygen measurement is started from the Watch's Health menu.

When the Blood Oxygenation function is activated, the red sensor remains on and fixed until the measurement is finished and the user returns to the Health menu of the Watch.

Note: the green sensor remains on permanently to be able to detect any arrhythmias in the user.  when the 24h monitoring is inactive, the green sensor on the Watch will only turn on every hour when performing automatic health measurements.