"I had to shorten some lengths of cast iron guttering and needed holes for the fixings. Normal bits would barely touch the cast iron. One of these bits did the job although it did take about an hour for each hole! Not sure I'd want to do it often but will definitely be using these bits if I do. Trick I found is to do it slowly and let the bit cool down regularly as it seems to cut better when cold."
"These bits are in a different league to standard twist bits.
Precise tip does indeed allow you position the hole precisely. It soon bites, and in wood, will plunge itself straight in. In fact it can be a bit too agressive, and you generally need to brace yourself to prevent it screwing itself into the workpiece. This also means some care is needed to give clean entry and exit in wood.
Bits are just as impressive drilling into steel. Very sharp and effective."