Hey everyone - I was watching ATP Tour Uncovered and they had a segment on stringing. The stringer was using this metal tool to tighten the knot. It wasn't the parallel jaw pliers on tw. It looked to be spring loaded where it clamps down on the string automatically. It almost looks like those hammers the doctors used to bang your knee cap to see if you have the leg reaction. I looked everywhere and can't seem to find it. Any one know where I can find it?