Rub discs that are unable to be replayed due to scratches with two types of cloths. Cannot be used with Blu-ray Disc and Preste 4 software. Just polish the scratch part. If you have a slight scratch, it can be repaired. For CDs, DVDs, and game softwares that give up play! Usage Notes: Cannot be used with Blu-ray discs. (The Software for the Preste 4 is the same as the Blu-ray disc, so it cannot be used. When washed with water, the active ingredients will dissolve, and cannot be washed with water. Do not use on printed surfaces. Print may come off. Cannot be used on discs where deep scratches reached to the printed surface.