Make sure the battery is positive and negative.
HealthTree Handheld Fingertip Pulse Oximeter, Rechargeable Pulse Oximetry, Finger Blood Oxygen Saturation Monitor with SpO2 & Pulse Rate, Portable Oxygen Meter Finger with Overnight Continuous
Pediatric Pulse Oximeter Heart Rate Stats Monitor Kids Finger Blood Oxygen Saturation Monitoring, Children SpO2 Levels Detection TFT Lanyard & USB (Blue Kids Pulse Oximeter)
Fingertip Pulse Oximeter, x2 AAA Battery(included), Carrier Case & Lanyard, Finger Blood Oxygen Saturation Checker Heart Rate Stats Detection, O2 Monitor Accessories for SpO2 Levels Detector
Fingertip Pulse Oximeter, x2 AAA Battery(included), Hook Carabiner, Carrier Bag & Lanyard, Finger Blood Oxygen Saturation Checker Heart Rate Stats Monitor Accessories for SpO2 Levels Detector
Pediatric Pulse Oximeter & Storage Zipper Case Heart Rate Stats Monitor Kids Finger Blood Oxygen Saturation Monitoring, Children SpO2 Levels Detection TFT Lanyard & USB (Yellow Kids Oximeter)
Pediatric Pulse Oximeter with Bag Heart Rate Stats Monitor Kids Finger Blood Oxygen Saturation Monitoring Children SpO2 Levels Detection TFT Lanyard & USB (Storage bag with Blue Oximeter)
