Tunable diaphragm technology -- a 3M invention -- lets clinicians hear different frequency sounds by simply adjusting the pressure on the chestpiece. Unlike two-sided models, there's no need to turn over and reposition the chestpiece. Hold the chestpiece with light pressure to hear low frequency sounds; press a little more to hear higher frequency sounds. This time-saving feature allows the healthcare provider to focus on the patient, while the non-chill rim provides patient comfort. 3M Littmann Stethoscopes are used by millions of medical professionals around the world who are dedicated to achieving the best patient outcomes. Littmann stethoscopes offer superb acoustic performance, consistently high quality, and outstanding value. Wearing a Littmann stethoscope is an expression of your commitment to medicine, and personal success.