3M Littmann TM Stethoscope Master Cardiology Black 00186 There is a small hole in the center of the diaphragm. This is to prevent pressure on the ears and to improve the movement of the diaphragm when the chest piece is pressed firmly against the body. This is a feature unique to the highest quality Master Cardiology. (Floating diaphragm specification) *The items in the image are all that are included. If you are interested, please consider purchasing. *Please refrain from comments asking for a discount on this product.