Dr. Emel did some surgery... clears now... shaved off a few grams... Writing says 142mm...Looks almost like a receiver for a quick-release clamp mechanism, perhaps for a bag or a light. Remove the screw and see what happens. If the red piece just falls off, chances are you can just get rid of it and put the screw back into the hole if it's not too long. What does the white writing say?