DIAMOND COATED: This cutting disc set is diamond coated and is designed for cutting hard surfaces such as glass, ceramics and most metals. FITS STANDARD 3.2MM COLLETS: It is supplied with two 3.2mm (1/8”) mounting mandrels that are suitable for use with standard 3.2mm (1/8”) collets. CONTENTS: 4 x 150 grit 16mm (5/8”) diameter diamond cutting discs and 2 x 150 grit 19mm (3/4”) diameter diamond cutting discs.