I now have two of these and they are very handy for clamping the flanges that are used to assemble the shell together. The flanges vary a bit in thickness so you are adjusting regular vise grips to get them to lock. These self lock on whatever thickness you close them on. You can adjust the clamping force with the adjustment screw in the middle of the tool. My only complaint is that when you go to lock them in place they open a bit wider than regular vise grips. Folks with medium or small sized hands may find them difficult to use one handed.