?Stethoscope?electronic sensor ,three Stethoscope modes Heart:20?230Hz Lung:100?800Hz H&L:20?800Hz ?Heart Rate Measuring range: 30bpm?300bpm Accuracy: ±2 bpm or ±2%(select larger) ?SpO2 Measuring range: 35%?100% Accuracy: 70%~100% ,±2% ?<70% unspecified ?Pulse Rate Measuring range: 30bpm?250bpm Accuracy: ±2 bpm or ±2%(select larger) Features: ?Compact and portable,easy to use ?Display of ECG waveform, heart rate,SpO2 ,pulse rate ,pulse waveform ?Based on latest piezo sensor technology ?Earphone output and 16 steps volume adjustable ?Alarm for SpO2 and pulse rate exceeding limits ?Low power consumption Specifications: ?Power Supply : ONE 3.7V Lithium Battery ?Display : 1.8" color LCD ?Dimension: 88mm(L)×60mm(W)×18mm(H)