1-13mm HSS Cobalt Jobber Twist Drill Bits Set for Stainless Steel Hard Metal (25 Piece Set). HSS Cobalt Jobber Twist Drill Bits. M35 high speed steel. Fully ground from solid material M35 alloyed HSS steel with 5% Cobalt content High heat resistance Manufactured to DIN338 Dimensionally precise 135° split point from 3mm and above eradicates the need to pre-drill or centre punch. Prevents walking and enables faster penetration. Suitable for drilling thick cast iron, tainless steel, aluminum alloy, non-standard metal, wooden plate, etc. Set Of 25 Cobalt Jobber Drills Supplied In A Metal Case For Storage Includes 1 of each of the following sizes – 1mm 1.5mm 2mm 2.5mm 3mm 3.5mm 4mm 4.5mm 5mm 5.5mm 6mm 6.5mm 7mm 7.5mm 8mm 8.5mm 9mm 9.5mm 10mm 10.5mm 11mm 11.5mm 12mm 12.5mm 13mm. 25,50,125,250. Piece Set Cobalt Jobber Twist Drill Bits.