Here is a group of 4 fishtail auger centering bits that I am selling together in one group.  I don’t know much about these bits, but 3 of them appear to be new, and one of them looks used.  The bit itself (not counting the threaded shaft measure 4” long and a little over 2” wide.  The shaft measures 5/8” in diameter.  Feel free to e-mail me with any questions you may have and thanks for viewing this listing.