Leveling frets
Use the 4″ length for spot leveling high frets. Start with 220-320 grit depending on how much material needs to be removed. Finish with standard 400-grit sandpaper, using double-stick tape to hold it to the block.
Beside this, can you sand down frets?
Smooth the frets with sandpaper.
Once all the frets are crowned, use progressively finer-grit sandpaper to sand down the frets and remove any scratches or nicks that occurred when you were leveling and crowning them. Start with 320-grit sandpaper, and sand the frets gently.
Furthermore, how do I know if my frets need leveling? If your guitar has dead spots, or areas where the buzz is noticeably worse in some areas than others, then you will benefit from a fret level, assuming you have enough height left in the frets to accommodate leveling (more below).
Hereof, how do you level a fret beam?
How do you level a high fret?
How do you level crowns and Polish frets?
How do you level frets at home?
How do you sand fret ends?
How do you use a fret sanding beam?
How long should a fret leveling beam be?
The 400mm one should be perfectly fine for leveling everything. I would even use the longer one for end beveling, too. That being said, my main leveling file is much smaller than that anyway.