After struggling with the stuffing box ,packing gland, on my sea ray boat several times. I broke out the calipers ,measured the packing nut and ordered this tool. I had been trying to used one of the so called adjustable packing nut wrenches purchased at the local Marine store to no avail. I had my stuffing boxes repacked and ready within 20 minutes using this tool. If you have ever had to repack a stuffing box on z drives you know what a challenge it can be. This tool made it simple and quick.