I took a chance despite other bad reviews. I just had to drill a hole in the cinder block wall. The shaft bent as soon as the nozzle teeth caught slightly. Without being able to straighten it, the adapter became unusable in the workplace. I tried smoothing it out. But without being able to pinpoint the accuracy, I'm afraid it won't work very well. Not sure why it even meets the recommendations given a concrete crown I bought at the same time. This adapter can work well when you drill wood. But nothing to tie or hook the bit with real grip. Judging by the time between ordering and using it, I couldn't return or exchange it. Too bad I ordered in advance. DO NOT buy this product. Please read all bad reviews and trust them. I had to drill a hole and even I would never rely on this product even for such a small job.