Vakind 10Pcs Metal Stone Tile Glass Engraving Tool Diamond Mini Needle Alloy Files Set Hardened steel shafts with non-rust nickel finish, embedded with industrial diamonds World's hardest abrasive surface - effective on hardened steel, glass, tile, stone Each file unique shape to cover full range shaping, forming, carving, engraving & material removal Size : 1.6* 0.4 Color : red