I used this nozzle to break up old grout on a chimney that needed to be diverted. I ground up most of the grout with a 5 inch diamond grinder. In places like head joints, I used this diamond-shined needle. He did a very good job. He quickly went through the crumbly loose solution. it took longer to grind down the cracks. The diamond grit held up well. I finished grinding and there was life left in the chisel. The long length of this chisel makes it possible to remove an entire stone. For my purpose I would have liked it to be a little about 1 inch shorter for better control.