I received it today as soon as it arrived. I opened two holes in a single pipe, I got one tip I managed to open a hole somehow, but I was disappointed that it was a bad method or a defective item.
I have opened Φ 20 already in 50 holes or more in steel material drilling (t 6 mm), but there is no problem at all. It is the first purchase with DIY. A commercially available drilling machine, cutting oil is cheap oil spray of Homusen. But one to four will be lost with 4 to 5 holes .... I bought two, but it may be good with one. I think that it is recommended privately.