Handcrafted Since 1971 | Lifetime Warranty | Free-Parts-for-Life Program | Latex Free. The MDF® Acoustica® Stethoscope delivers accurate auscultation of heart, lung, and Korotkoff sounds with acoustic integrity and clarity. Chestpiece: The super-duty, lightweight aluminum dual-head chestpiece is precisely machined and hand polished. Full-rotation acoustic valve stem with green indicator dot identify the active sound channel. The large bell, crowned with a non-chill bell ring, provides greater sound amplification, isolation of low frequencies. Tubing: Constructed of thicker, denser, latex-free PVC. Patented Acoustic Pyramid Chamber®: Made of metal-alloy located in the acoustic tubing below the spring keeps the tubing channel open for maximum sound transmission into the headset. ErgonoMax® Headset: Hand polished, pre-angled chrome-plated. Patented SafetyLock® eartip adaptors lead the industry in user safety. Included Accessories: ComfortSeal® eartips, diaphragm, and ID tag.