Fretboard Markers Inlay Sticker Decals for Guitar - Bloody-Line Material is PET You can install these on your electric or acoustic guitar with 24 3/4 inch(628mm) 25 1/2 inch(648mm) guitar. They will not get caught by your fingers while playing! No adhesive is left behind if you peel off the sticker. It is fit to any type, 21 frets,22 frets and 24 frets!!