Xiaomi just unveiled a brand new wearable device, the Xiaomi Mi Band 2. Despite the name, it’s the company’s third fitness tracking device after the Mi Band and Mi Band Pulse. It track your steps, monitors your heart rate and (for the first time) features a tiny display. It costs RMB 149, or a little less than $23.
The new Mi Band 2 improves on the last heart-rate tracker with an “upgraded pedometer algorithm” and a 20-day battery. The band is also water resistant. Optical heart rate sensors typically work by shining an LED light into the skin and measuring how the light is scattered by blood flow.