As a result of my tests I determined that this drill bit is a waste of money. It did not perform as advertised and barely made a dent in the wood. The only pro is that IT was easy to attach to my drill .The con is that it did not live up to its promises and left me with a frustrating and disappointing experience..
The carbide tip broke after the first use. I bought two because I knew I could break the barrel of a 3mm nozzle, but I never expected the tip of the pen to actually break. Carbide is a strong material, but it is very brittle.