Color-changing when holding warm fluids.

From the collection of a previous Northrop employee

3" mouth diameter

"Out of the Black" is with a dark background, then when you fill the cup with a hot fluid, it changes to "Into the Blue" with a blue background

First flight Palmdale to Edwards Air Force Base 1989

Previously owned, as-is.  No chips or cracks.  Color change works with heat.  See attached pictures.