Fidelis Healthcare Machine stainless steel chest piece, Double sided chest piece technology. Diaphragm diameter 15 cm diaphragm diameter 3 cm (1.25 inch approx) reliable & high acoustic sensitivity offer an advantage to health care professionals when listening to heart, lung and blood pressure sounds. Type: Acoustic Dual-Sided Chest Piece For Clinician, Diagnostic, Physician, General Practitioner, Nurse