The Columbia Dentoform 1KUM81 U-M-8-1 Universal Ball-Joint Rod is a replacement mounting component designed for the Columbia Dentoform M-8-1 small bench-mount system. The universal ball joint allows the attached dental manikin or typodont to be positioned and adjusted for realistic dental training and student practice.
The associated M-8-1 mount is a portable, bench-clamp mounting system that uses an approximately 11-inch rod and is compatible with Columbia Dentoform manikins and typodonts. The image above shows the ball-joint rod installed as part of the complete M-8-1 mounting assembly; I did not find a verified isolated manufacturer image of the replacement rod alone.