Nixie tubes are the little glowing anodes (original and still frequent color red) that are characteristic of a Light Emitting Diode (LED), enabling you to read your clock radio and many other such glowing devices that have the ability to change display.
"What else can you do?"
"Look for the kind that glows a color on a dark background. The display is often but not necessarily red in color. The little bars that form the LED display are called nixie tubes ."
"Now, what are the odds the folks down at the Shack will know that?"