Operation Instructions1. Install a pair of AAA batteries into the battery compartment2. Plug a finger into a rubber hole of the Oximeter.3. Press button on the front panel to start4. Do not shake your finger or move your body when the Oximeter is working5. Press the button if you want to change display direction6. Read the relevant value from the display screen7. The device will automatically power off in 8 seconds if there is no finger signal