I purchased two 4" vises to be used together on a small Grizzly mill. The size it just right for the machine. I like the fact they provide keys so you can trim the keys to fit the table. The keys also provide a positive lock to keep the vises in-line while working. The -1 star is because of the height difference in using a pair on the machine. The vises are not book ends to each other. My examples are .012 different in height so I will have to shim 1 vise so they are the same working height. The milled keyed areas under the vise are not the same to each other as well. Also 1 handle was not broached all the way therefore it would not slide onto the hex vise screw fully. So the vises need a little TLC before using them for other projects in the garage. I'm happy I didn't spend $1000 for kurt vises when with a few hours of tuning these vises will be more than fine for my intended machine. These vises are not for real CNC work as the vises are not held to the tightest tolerances. For the price they can't be beat.