Sometimes you need to drill through walls for wiring access. Phone, cable TV, and internet use, all require their own access point. Most drill bits won't reach. This gadget does a beautiful job. It's solid steel and feels heavy. The allen wrench does a good job of holding the bit solidly, too.One small problem; the head of the extension is about 5\8 of an inch in diameter, and the two small set screws will typically project another 1\16 of an inch, or so. This sets a limit on how small a hole you can make with a full reach. Still, I consider this extension a must-have in a drill kit. Very solidly made, should last forever. Quick delivery, too.