I normally mask off the fretboard and use fret rubbers and very fine sandpaper to do frets. I got these as I reckoned they would be faster. They would be I suppose but after doing a few frets on a guitar I began to notice very small little cuts in the fretboard where these 'savers' had been applied for fret cleaning/polishing. So, I stopped using them and went back to my old but slower method. I am a guitar tech and do a lot of guitars and feel these might be ok to use on a cheapo guitar you have modded to go out gigging with but in all honesty, I will not be using them on a mid or expensive level guitar again. The slower and older way is better and will never leave marks.