Trephine used by Dr. Ben Carson

This trephine was used by Dr. Ben Carson. It is two (2) inches in diameter with a black metal base with a silver rim, and a silver metal shaft. The bottom edge of the base is serrated. A metal drill bit protrudes from the center bottom of the base and is adjusted with a tension screw on the side of the shaft. The text "CODMAN REPAIR 3Q91" is printed on the side of the shaft. A trephine is a surgical saw used to cut a hole in a patient’s skull.