The trephine has a brass shaft. The top of the shaft- handle ends- is square. After the square end is a round knurled disc. The shaft then indents in and back out until it reaches the blade end. It then flattens out to the diameter of the blade. On one side of the shaft is a curved blued steel rectangle with inward curves. IN the middle of this rectangle is a brass thumb screw. This acts as adjustment for the internal blade. The round blade is round and has serrations.