This replaced a 4" vise on my Harbor Freight mill, and "wow" what a difference. I had to mount it perpendicular to the table due to the large size (about 17"x9"), and the mounting holes didn't line up with any of the groves. However it holds the work very securely and doesn't move around at all. Fortunately it comes packed in styrofoam as the package was badly beat up, so the vise arrived updamaged.