All four bits broke before I could drill the first hole like they were glass. I've never had parts that fail so quickly. I will never buy from this seller again.
I wish these guys/girls would make taps that work with drill bits - drill effortlessly through stainless steel that breaks so-called 'industrial cobalt'. popular brand as if they were branches. I see a few reviews that say they've become garbage after a few cuts, so I'll update my review when that happens. But so far I've been impressed with the price, performance and sharpness.