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.
In addition, the TicWatch Pro has an IP68 rating for water and dust resistance, along with its own heart rate monitor and GPS hardware. It has the Qualcomm Snapdragon 2100 processor inside, along with 512MB of RAM and 4GB of onboard storage. It’s available now in either black or silver colors on Amazon for $249, but at the moment it’s exclusive for members of Amazon Prime until August 15. You can read a lot more about the TicWatch Pro in our extensive review.