Mysterious Things Could Even Puzzle Sherlock Holmes

 Belt Tool

WITT found in older tool box (at least 10 years old). part with spokes rotates, spokes (of different diameters) match up to hole in the oposite side of the tool. Sharpie marker for size.
Answer (by u/brock_lee): It is for punching holes in leather or similar things. Like, for a belt.