Well received my medical grade vascular doppler ultrasound machine.
And like hyenas car service manuals HERTZS mater when buying ultrasound dopplers.
Mine is 5 mhz ultrasound doppler and you can hear the stress building when listening to juices flow threw ya vain's.
Lucky for me i have genetic condition where my vains are tad bigger than usual CAN'T really remember name of it but its something to do do cf so called healthy trate carrier status.
Anyway had doppler on my heart and gosh if my heart was engine and be very proud.
I could hear all four cylinders firing ITs quite a sound if can cope with stress of hearing your heart.