Perfect for metalworking and keymaking diamond files are a specialty tool which is best suited to grinding brittle or extremely tough materials this makes diamond files perfect for glass ceramic and hard steels technical specifications file length 140 mm length of hips 70 mm tip diameter 1 mm max thickness 225 mm includes 2x flat 2x round 2x halbrund 1x square 1x triangular 1x knife files 1x cowling files 1x storage roll bag ideal needle or key file set