Inside the Charge 3 are an accelerometer, gyroscope, optical heart rate monitor, and an SpO2 sensor for tracking blood oxygen levels. The Charge 3 is the third Fitbit device to include an SpO2 sensor, following in the footsteps of both the Fitbit Ionic and the Versa smartwatches. However, currently the SpO2 monitor lies dormant inside all of these devices as Fitbit hasn't made use of it yet.
Finally, Wear OS has a problem that’s seemingly random and hard to understand: “Can’t reach Google at the moment.” Having tested at least a dozen Wear OS watches, we can say that an unexplained failure when using voice commands is the most common negative trait for all of them. It’s impossible for the layperson to understand which part of the watch-to-phone-to-Internet relay is falling down, but it can happen at any time, even right after you’ve used the watch to do something else successfully. When Google Assistant is made the center of Android watches, not being able to reach Google Assistant lowers the value of that watch considerably.
Our top pick for most people is the Apple Watch Series 4 with GPS (starting at $399), which has a huge display, ultra-fast processor, Raise to Speak Siri, fall detection and a built-in electrical heart rate sensor for taking on-the-go electrocardiograms. It also runs watchOS 5, which makes the watch even more useful with automatic workout-tracking, offline podcast playback and a Walkie-Talkie voice chat feature.