This time around, we've dug up another gem from our own Sibley shop. Powered by four D-cell batteries, this hand-held inspection tool was used by savvy garage owners to demonstrate to customers that a particular item was past its useful service life. We've omitted the brand and the tool's name, but both were originally printed in white on the tool's black top box. The tool's name was even printed on the side, in case a customer asked, "What is that you're holding?"

The black top box measures 4.75″ long at each side, curving to 4.25″ long in the center. The box measures 2″ high, and slides in or out in regards to the fixed-placement lamp. At its farthest point, the mouth of the box is 1.5″ away from the shade of the lamp, while at its closest point, it's atop the lamp's shade.

More clues, photos and the answer on Hemmings.