You clipped the excess off a screw and are left with a ragged end. In oldie days you’d reach for a riffler or spoon file. Too often the file would slip off the screw and drive itself into the frame or lens.
Now you don’t have to take that chance. A few twists of this tool’s cupped serrated cap will safely round off the ends of cut screws. The working end is made of hardened carbide steel permanently mounted in a carbon steel nickel plated handle.
Works on screws with a maximum diameter of 1.6mm. Also use to smooth the ends of cut temples.