Please check and Ensure you are buying the correct Spare Part for your 3M Littmann Stethoscope. Sizes are different.                                                                                      3M? Littmann? Stethoscopes offers the high quality that medical professionals expect, and each replacement part and accessory meets the same demanding standards. Conveniently packaged in kits that correspond to our stethoscope models, Littmann stethoscope replacement parts and accessories make repairs simple.? Each item is carefully manufactured to work seamlessly with existing equipment.