Fitbit Charge 4 update adds new on-device functionality
According to the official changelog, Fitbit Charge 4 users will finally be able to estimate their blood oxygen saturation (SpO2) while they sleep from their fitness tracker. Up until now, checking SpO2 levels was only possible from the smartphone via the Fitbit app.
Another change included in the update is probably just as important, but for entirely different reasons. Firmware version 1.100.34 brings the ability to view a device's activation date, which is the day the wearable device's warranty begins. Just so you know, the activation date is the day that you set up the Fitbit Charge 4.
To benefit from the latest changes, make sure that your Fitbit app is on version 3.39, otherwise, you won't be able to download the new Charge 4 firmware.