No, the band cannot measure HRV, sleep quality and stress levels. According to the manufacturer, COROS watches do support HRV measurements, but these are carried out via the watch's optical sensor or an ECG - external sensors such as the heart rate monitor are not used for this purpose. The official product data shows that the heart rate monitor only transmits the heart rate. For sleep and stress analyses, you need a compatible COROS watch with the corresponding sensors.