This module consists of a Bakelite plug with two rows and eight columns of contact pins, four rows of solder terminals on each side, and eight tube sockets on top. There is a rod that extends from above the tubes to a cam on the bottom to lock the module in place. Components are mounted vertically between adjacent solder terminals. All eight sockets are wired, but only two are populated. On one end of the Bakelite connector there are yellow marks made with a magic marker.