I have a set of standard length (6") Bosch DareDevil spade bits and need them to drill a hole in wood posts about 6" in diameter . Corner of the room for new wiring, just a little deep for standard length. I got this extension despite some pretty negative reviews. It worked great. It held up despite the heavy drilling and I had to use a percussion tool instead of a drill to finish the hole. The set screws are not what I want, but they work and you don't have to tighten them unnecessarily. The connection to the paddle attachment held tight under considerable torque and did not loosen when I pulled back to remove the attachment. The advantage over some others I've seen is that the cross-section at the junction is small so you can use it with small bits, while the others I've looked at have a thick connector and not smaller ones bits can be used . blade diameter. The DareDevil shovel bits themselves are terrible at the way they bite through wood. They are also very happy. This is a very good value item and I would definitely recommend it.