-Patented tunable diaphragm alternates between low- & high-frequencies without turning over the chestpiece by alternating pressure. This allows for same-site auscultation. -Hand-polished, scratch-resistant finish. -Reinforced double-leaf spring & thick binaural provide extra durability. Lightweight, adjustable-tension headset, & patented 3M Littmann Snap-tight Soft-sealing Eartips. -Chestpiece is finger-contoured for easy-grip, secure hold. -Easier to auscultate under a patients gown. -Nonchill rim and diaphragm assembly for patient comfort. -Thick 27. inch, single-lumen tubing provides excellent portability, allowing you to fold the stethoscope easily into your pocket without kinking or breaking. -Three-year warranty.