Next generation fret files A whole new idea for crowning frets. Z-File Fret Crowning Files ™ won't mess up your carefully-leveled fret tops because they only touch the sides of the frets. Won't cause string buzz. After you've leveled the frets for uniform height, your crowning file restores their rounded shape, leaving the thinnest possible line of leveled surface on top. This is when other crowning files can accidentally scrape the fret top, creating a buzzing low spot. Z-Files don't have this problem—because they don't touch the top of the fret. Z-File features: Fast cutting 300-grit diamond abrasive Unique angled cutting edges work the sides, not the tops Our Centered Z-File has two diamond edges in a centered V-shape that cut both sides of the fret at the same angle. Simple to use and fast working. Works on stainless frets, too!