Finger Pulse Oximeter, (SpO2) Blood Oxygen Saturation Monitor with Pulse Rate Measurements and Pulse Bar Graph, Digital Reading LED Display : Health & Household - Amazon.com
ANKOVO Pulse Oximeter Fingertip, Pulse Oximeter Blood Oxygen Saturation Monitor and Heart Rate Monitor, Easy to Use, Portable Pulse Ox with 2 Batteries and Lanyard (Royal Black) - Walmart.com
Measuring heart rate and blood oxygen levels for portable medical and wearable devices - Embedded Computing Design
Pulse Oximeters and Coronavirus: Devices Have Higher Error Rate in Black Patients - The New York Times