"With its European quality cup bur, this simple to use tool is perfect for smoothing the rough & often sharp ends of cut wire.
Round the end of rough or pointed wire with this cup bur tool. (A cup bur is a very small, cup-shaped file which works perfectly on the ends of wire to smooth sharp ends. You will get a lot of use out of this little tool!)
Just twist the hardwood handle while holding the cup on the end of your wire. The cutting surfaces that smooth the wire are inside a 1.8mm cup. Designed for soft wire such as sterling silver, copper or gold-filled wires."