Principle : auscultation of the human heart, lung, veins and other organs of the sound changes through the stethoscope hair the sound vibration, transmission measurements of the ears had to effectively distinguish the sound changes.

Product features : listening to the first use of forging die derived tissue density, not sand pits, voice communication clearer.

Hose and listened to the first screw connections using packet hoop connected to prevent leakage of voice,

Fanning auscultation first used in auscultation high pitch noises.