I bought this for use with my machinists granite plate while checking the flatness of various tools in my shop that need to be really flat. This was a fair bit cheaper than what is labeled as the 'proper' stuff yet seems to do the same job. I use a rubber brayer to roll out a small amount onto my granite plate and then transfer the ink to the high spots on any given tool to know where the high spots are. One example is when assessing the flatness of an old cast-iron hand plane that I might buy at a flea market. This could be messy if mis-handled but seems easy to clean up with a little mineral spirits on a paper towel.