This part is a kind of semiconductor called KY202M.

Function of this product has Heart Rate Variability Processing Module.

Manufacturers : K&Y Lab

Image and pinout :

Some of the text within the PDF file :

Model : KY202M Heart Rate Variability Processing Module Module Features 9 9 9 9 9 9 9 9 Weight : 0.88 g Dimension : 17mm x 20mm UART link ( TTL level Tx / Rx / GND ) Easy PC or Micro Controller Interface Time and Frequency Domain Analysis of Heart Rate Variability Instantaneous Heart Rate (IHR) Standard Deviation of R-R intervals (SD) High-frequency (HF) and Low-frequency (LF) powers of R-R interval variability ‧ KY202A: Heart rate ‧ KY202B: Heart rate and standard deviation ‧ KY202C: Heart rate, standard deviation and frequency domain analysis 9 9 Low Power : Input Range 0 to 2.5 V with Single 2.7~3.6V Supply Low power consumption (active 4 mA, power down 1 uA) GND Tx Rx +Vcc Temperature ECG 1 Model : KY202M Heart Rate Variability Proce [ ... ]

KY202M PDF Datasheet Download