6pcs SAE Drill Tap Combination Bit Set Deburr Countersink Hex Bit HSS 1/4 Shank Package Included:6pcs Drill Tap Countersink Set Material:High speed steel SAE Size: 6-32NC(3.5mm),8-32NC( 4.2mm),10-32NC( 5mm),10-24NC( 5mm),12-24NC( 5.7mm),1/4-20NC( 6.35mm) Shank Dia:6.35mm 1/4 Hex Shank Suitable for soft metal tapping, such as aluminum plate, thickness of less than 3--4mm.