This is a precision measuring tool used for accurately measuring the outside dimensions of objects.
The micrometer shown has a measuring range of 0-1 inch and a graduation of 0.0001 inch, indicating high precision.
It comes with a wrench, likely for calibration or adjustment.
Such micrometers are commonly used in mechanical engineering, machining, and metrology.
You can find similar outside micrometers for purchase online from retailers specializing in tools and precision instruments.