1PC Heart Rate Sensor Module GY-MAX30100 Puls Detection Blood Concentration for concentration sensorFeatures:brand new and A measures the saturation in the bloodstream. Since blood saturation can reflect early problems such as heart and lungs, this reading is very useful as a general health monitoring metric.Its working principle is based on the light-absorbing properties of hemoglobin in the blood. Oxyhemoglobin absorbs more light than light, while deoxyhemoglobin absorbs more light than light. Therefore, the and LEDs in the alternately emit light, and the photodiodes receive the light that is not absorbed. The ratio of and light received by the photodiode is used to calculate the percentage of in the blood. According to the pulsatile nature of the arterial blood flow, the rate and intensity are also determined and displayed during the measurement.Optical sensor: and LED combined with photodetector.Measures absorbance of pulsing blood.I2C interface INT pin.3.3V-5V power supply.Specifications:Material: ABSLength: approx. 3cm/1.18inPackage Includes:1 x Heart Rate Concentration SensorNote:No retail package.Please allow 0-1cm error due to manual measurement. pls make sure you do not mind before you bid.Due to the difference between different monitors, the picture may not reflect the actual color of the item. Thank you!