No value of blood oxygen

Check whether the sensor on the back of the watch has red light when measuring blood oxygen
1. If there is no red light, please follow the after-sales process
2. If there is red light, but the value is often not measured or the value is not accurate, please wear it correctly for measurement: put your arm flat on the table and lift it a little. The wearing position of the watch is 1 finger away from the wrist bone. Relax and keep still. Don't talk during the measurement, and ensure that the equipment is close to your wrist (wear it a little tighter)
Note: when worn correctly, individual differences such as skin color, hair, tattoos and scars may also affect the measurement accuracy. The value measured by the watch is only for reference and cannot be used as a basis for medical diagnosis