"Abbott Octagonal shaped tombstones are made of Tenzaloy\u2122. They provide a practical, inexpensive and lightweight means of holding work accurately in a vertical or horizontal application for CNC machining operations. They can be mounted directly ...
"Chuck bungs are primarily used to block the centre of the chuck to stop swarf and coolant going down the spindle. The threaded hole which can be used for the removal of the bung can also be used for mounting a back stop."