Full Specification ( Automobile Stethoscope ):

When components of an automobile engine are not functioning properly, they usually sound a warning in the form of noises not common to normal operations. Fortunately most noises posses characteristics of their own which help to identify the sources, coupled with some knowledge of their meaning. The unit is consisting of earphone, amplifier, switch and carbon microphone, assembled in a polished wooden box, Furnished with instructions, and a chart of possible different noise, probable source, mike position and how to check.