I am currently restoring a 100+ year old piano which has been VERY badly neglected and wanted to see if it was possible to tune it. Not wanting to spend a fortune on a tuning hammer for a piano which might not tune, I decided to try this one and was pleasantly surprised. The tool is of a decent quality and worked well, I was able to apply quite a hefty amount of pressure on it occasionally to free up a few seized tuners and it coped with it easily and it didn't threaten to round off the square heads as it was a really good fit.
Very happy.