A tough cobalt alloy delivers heat resistance up to 1100 degree Fahrenheit allowing the bit to perform for extended periods of time in the most abrasive materials without failing due to the high heat levels. Overall bit hardness of 66-68 HRC from the cobalt formulation gives the ability to penetrate exceptionally tough materials
135 degree split point starts on contact with no walking or skating and no center punch is required
These bits work where no others have. I drill a lot of hardened steel and generally treat most drill bits as disposable, which gets expensive. These cobalt bits have took a beating and are still as good as the day I purchased them.
I recently broke a lesser quality bit while building a project. It involved drilling thin steel. When it broke the part left in the drill went into the top of my thumb. It went through the nail below the cuticle. I got it stopped before it went through my thumb completely. Needless to say I have some damage to my nail bed now that is permanent.Puncture wounds heal slowly and not without pain!!!!!!!!!!!!! Vowing to replace my bits with QUALITY, I chose this Bosch set because of the name. I am not disappointed!! These bits have given me a whole new appreciation for what quality tools bring to the table and NOT my thumb!! If you are looking for quality at a reasonable price this set of bits will fill the bill.