The blood oxygen saturation and pulse rate of the human body are measured by fingers. New crown must have at home! Simple to use: Hold your finger, turn on the oximeter, and after a few seconds, you can read the measurement results directly from the screen, and automatically shut down after no contact. 2pcs AAA universal dry batteries (product package without battery) Measuring range: Pulse range: 30-250BPM Blood oxygen range: 1-100% Measuring distance: 5CM-15CM Accuracy: Pulse accuracy: ±1% or ±1BPM blood oxygen accuracy : ±2% Voltage: DC2.6-3.6V Now accepting reservations about two weeks in stock