In China, since around 2015, smartwatches have become widely used by schoolchildren. They are advertised on television throughout the country as a safety device whereby the child can call in case of emergency. The devices are commonly colorful and made of plastic. They normally have no display unless a button is pushed. These smartwatches have limited capability compared to other smartwatches; their main functions consist of being able to conduct calls, displaying of time, and sometimes have air temperature sensitivity. They cost around $100 to $200 USD.
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.
The Apple Watch Series 4 is now on sale, and it's the best smartwatch you can buy right now. The redesigned device, which starts at $399 for the GPS model and $499 for the cellular version, is the best smartwatch you can buy. It has a larger display and slightly bigger case size while retaining the same rounded square design the watch is known for. Even more importantly, Apple received FDA clearance for a new electrocardiogram feature that can take a 30-second EKG and diagnose atrial fibrillation.