Fingertip Pulse Oximeter Digital OLED Blood Oxygen Saturation Monitor with Lanyard Condition: Item Type: Fingertip Pulse Oximeter Material: ABS Power Supply Mode: 2 x AAA battery (not included) Instructions: 1. Load two 1.5V batteries according to the positive and negative signs in the battery slot and close the battery cover; 2.Pinch open the clip of the finger clip pulse oximeter, insert your finger into the rubber channel (the finger should be fully extended), then release the clip, and click the switch button on the front panel; 3. Do not shake your fingers during use, and it is best not to move the human body in order to read accurate data; 4. After booting, the interface direction switch defaults to the button mode, short press (less than 2 seconds) the button, you can switch in a fixed order in 4 directions. 5. Automatically shut down after 8 seconds without finger induction.