This module has six miniature vacuum tubes and two neon bulbs mounted on a chassis located at the extraction end and a phenolic board holding 36 bannana plugs that serves as the insertion end. Components are mounted in the 3.5 inch space between the chassis and insertion end. Each of a pair of tubes on one outside end appear to have identical circuitry, and each of a pair of tubes on the opposite end appear to have identical (but different) circuitry. The center pair of tubes are each wired differently. A small paper tag attached to the extraction handle has dates and numbers that appear to be test results.