I purchased this tool because I needed a 2" wide drill bit extension that would allow me to remove deep debris from an existing post hole. This tool has two set screws, one of which required a lot of force to mate with the SDS bit shank; (The hole was not threaded properly). The threaded pins were already damaged after one hole, making the extension unusable. I decided to hire a professional welder to weld the extension to the weld. The weld turned out very well. But again, the extension broke clean after just one hole, where the shaft tapers and the SDS slots begin. This indicates that the overtime was poorly made and very weak. Bit and extension cord is useless. I can't even return the extension because it has been modified! Save yourself a lot of time and frustration; Purchase a Milwaukee 12-inch SDS bit extender that has an SDS shank on one end and a narrow SDS chuck on the other end. This is a more expensive but much better tool.