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. Seven sockets are wired, but none of them are populated. One socket is replaced with a to-pin crystal socket, which is populated with a 1323.280 Hz crystal.