Handcrafted Since 1971 | Lifetime Warranty | Free-Parts-for-Life Program | Latex Free. The original MDF Pulse Time Stethoscope with timing apparatus enables medical professionals to maintain eye contact with patients during diagnosis.(USA pat. no. 5252787 & China pat. no. 87572) Chestpiece: Equipped with a 24-hour liquid crystal analog (LCA) quartz timepiece. Made of lightweight anodized aluminum. Tubing: Constructed of thicker, denser, latex-free PVC, Y-configuration non-stick acoustic tubing. 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 brass headset features a patented internal dual-leaf spring. Patented SafetyLock eartip adaptors lead the industry in user safety. Included Accessories: 2 extra sets ComfortSeal eartips, fiber diaphragm, and ID tag.