A holdfast is a tool used in woodworking to clamp a workpiece to a workbench securely. It is handy when you need to keep wood in place while you saw, plane or carve. The holdfast has a steel shaft with a flat head that presses against the wood and is inserted into a hole in the workbench. To secure your project, you strike the top of the holdfast with a hammer or mallet, which causes the metal shaft to expand inside the hole and clamp the workpiece firmly. When you're done, a light tap in the opposite direction will release it.
The Narex Holdfast is a practical tool forged from carbon steel. It is designed for round holes in workbenches with a diameter of 19mm (3/4"), which is standard in most dog holes.