Cardiology Classic offers acoustical excellence in a traditional design. Its innovative features include: - stainless steel chestpiece (Ø 36-47 mm) with extra deep cone-shaped bell for a superb low frequency response - stainless steel double inner spring binaural - floating diaphragm for unsurpassed amplification - durable, elegantly moulded Colour co-ordinated non-chill ring and diaphragm retaining ring PVC black tubing.