This is one of the nicer spade bits we have ever seen here. Its unique threaded design allows it to pull smoothly through all materials. It's simply called a Self-Feeding Spade Bit, 5/8in diameter, Hex Shank 1/4in. It can be used with Greelees line of drill bit extensions. It even has a wire fishing hole, in the end, to make pulling the wire back through the hole quick and easy.