The Classic II Pediatric and Infant stethoscopes feature the floating diaphragm technology. All models feature single-lumen tubing, nonchill rim and patented Littmann soft-sealing eartips. To help clinicians be sure they are obtainig a genuine Littmann Stethoscope, all acoustic (non-elecronic) stethoscopes with a 2007 lot code (or later) will carry a 3MTM ConfirmTM Authentication Label with Floating Image. Three-year warranty.