Red and gold

Answer revealed, winner: littlecow, click comments for answer. Scroll down for original.

A new puzzle. Identify.

My vacation was short, but great. Sorry for the long wait, folks. You can expect more frequent posts now.

UIO

Answer revealed, winner: littlecow, click comments for answer.

This is not commonly known, but it is an internal part of something else that is commonly known, hence it is an unidentified internal object. Let's see if you can identify it. 3 guesses / person / day.