Maico Stethetron, an electronic stethoscope, model MS-1. The chrome stethoscope plate attaches by wire to a battery pack. A light blue paper package contains an extra plug. A red paper instruction sheet reads (on front) "Heart and chest sounds 10,000 times louder with the tiny new Maico Stethetron, worlds smallest electronic stethoscope." The pack measures 11 cm x 4 cm x 2.2 cm. Provenance is unknown.