The module is a box formed from two printed circuit boards mounted on a three-sided metal frame. The circuit boards are mounted facing each other with the circuit sides out. Each board has a male connector with two rows of 15 pins attached to one edge. These two connectors form the fourth side of the frame, on the bottom of the module. The top of the frame has two protruding 'ears,' presumably to facilitate extraction of the module from a backplane. The top also has a single banana-plug socket, and a hole presumably for air circulation. There is a matching hole in one side of the metal frame, which aligns with the holes in the plenums of the backplane, object 102735636. One of the boards is just over half-height, revealing one tube socket mounted perpendicular to the other board, so that a plugged-in tube is contained within the module. The socket contains a vacuum tube. The edge of the short board has been color-coded with a thin green stripe.
Communication Measurements Laboratory, Inc
Printed on two white paper labels affixed to the top of the module frame.