Had bought mainly because of the extremely low price of the stethoscope and would not do again. Listen for defective combustion engines, may suffice this part, but the heartbeat can be heard very weakly and in some people, you can sense him more. So it was partly not possible for me to identify with this stethoscope the exact heart rate. My personal recommendation: rather just an expensive purchase before rumärgert with a cheap part. But was not too cheap, but there was no indication of the operation, because when I found out by accident, how and where you have to rotate the part, everything worked really well.
