Think of a fret-level like race-tuning your car's engine. A fret-level is is a process whereby a guitar tech or luthier, removes the strings from the neck of a guitar and and sands the frets across the entire neck, usually with a sanding block to attempt to make all the frets perfectly level. Sounds good in theory. But there's an inherrent problem.

When the guitar is re-strung and brought up to tension (and tuned to pitch) the neck starts to move, as it's supposed to, into its very slight upward bow. More likely than not, when the guitar is played it buzzes. For most luthiers or guitar techs, this is standard practice. They then remove the strings and try again. They get close but they never quite achieve a perfect fret level. Why? The standard fret-leveling procedure does not take into account the final upward curve of the neck at tension, when its being played.

The Katana system allows our guitar techs to leave the strings on, at tension and the guitar tuned up to play. The Katana tool is positioned on the neck and adjusted (it also has a truss rod inside) to match the curve of the neck. It's then further positioned between the strings utilizing its clever design and the guitar tech begins sanding the frets. Once the sanding is complete and prior to any fret dressing that is needed, the guitar tech can play the guitar, as is, to see if they've sanded enough to eliminate high or uneven frets.