Stethoscope Duplex by Riester for the auscultation of newborns and infants. Riester Stethoscope Duplex – NeoNatal Specifications: – Double-headed chest-piece with specially lightweight aluminium, galvanized. – Special membrane for perfect auscultation, Ø 28 mm, with particularly flat and soft non-chill rims for improved adaptation on the skin. – Bell, Ø 22 mm (0.9 in). – Overall length: 76 cm (29.9 in). – duplex® neonatal comes with a pair of replacement ear-tips and a replacement membrane.