From Leading German Manufacturer KEIL

HSS-E DIN 338 Cobalt 19PC Set
1mm - 10mm

Centre punching is not necessary.
Direct drilling without prior centring or drilling of a pilot hole.
Safe pilot hole drilling, even in slanting surfaces, in pipes and welds.
The feeding power is reduced by up to 50%.
The drill bit facilitates an increase in drilling progress by up to 45%.
Even chip removal and reduction of chip friction.
Extremely true running and precise round holes.
No jamming of the main cutting edge and no slipping of the drill bit with through boring holes.
High fracture strength and long tool life.
Reduced friction due to reduced diameter in the shank direction.
Higher breaking strength through conically reinforced drilling core.
Long operating time and fast drilling progress through chemical thermal method of hardening and accurate cross-ground finish.
Due to the alloying addition of 5% Co these drill bits are well-suited for work pieces with a tensile strength of more than 800 N/mm2.
Extra high temperature strength to cope with suboptimal supply of coolant.
Up to 20 % higher durability than identically constructed HSS drill bits used under the same operating conditions.
Suitable in all rotary and percussion drilling machines and machines for mechanical processing.
Only for rotary use, NO HAMMER ACTION REQUIRED.