BlackSmith M64 fret polishing kit is safe on all metal fret wire. M64 fret polishing kit includes M25 fret polishing cream, M19 micro fiber, and M20 fret guard gauge. Oxidized frets damage the strings and reduces short string life. Our fret polishing kit removes dirt, grimes, and also turns to original color. With BlackSmith fret polishing kit, you will experience perfect sound and play-ability.​ ​