Professional tool for commercial or occasional use We use these sets ourselves in our trailer manufacturing company. HSS 4241 for strength and durability. DIN standard 338 135 degree split point drills 99pc set Split point drills for accurate and precise work SET INCLUDES THE FOLLOWING SIZES 1.5mm HSS Drills x 16 2mm HSS Drills x 16 2.5mm HSS Drills x 15 3mm HSS Drills x 10 3.2mm HSS Drills x 10 3.5mm HSS Drills x 8 4mm HSS Drills x 8 4.5mm HSS Drills x 3 5mm HSS Drills x 3 5.5mm HSS Drills x 2 6mm HSS Drills x 2 6.5mm HSS Drills x 2 8mm HSS Drills x 2 10mm HSS Drills x 2 All High speed steel drills so suitable for most materials including steel / aluminium / copper / wood / plastic etc... Comes in a fully marked metal tin for easy storage / transportation and easy finding of the correct size drill.