Steel instrument with two sides that are connected by a joint- one side can be swung open. One side has a open paddle connected to a threaded post. The threaded post is held in the instrument with a thumb screw. Open the inside of the post mounting is a platform that meets up with a point on the other side of the instrument, so it cannot close all the way. The other side is a similar open paddle. This paddle moves back and forth on a screw, and is held in place with a hand wheel on the top. Both paddles are covered in what appears to be plaster.