I have a tool that I don't know what it is. Its a square tapered rod 2 7/8 " with a groove about 1/32nd " in from each corner. It says 15/64 drill and is just less that a quarter " square before the taper. So, how do you use it and what does it do. Thanks for any explanation. Is it an easy out? Seems like it would grab if inserted into a 15/64 hole in a stuck bolt and rotated counterclockwise. Jeff Valentine