Those HSS-G precision drill bits they are special for a very specific reason.
The word precision is the keyword, they have just a bit of extra hardness but their edge is actually sharp like a knife.
When you do assembly or actually manufacture customized electrical power boxes, or control boxes loaded with small switches, or even working with aluminum panels about making again custom designs, there is no better drill bits than the HSS-G.
The correct use of the drill bits is almost a small chapter of theory.
Factors like high temperature, wrong RPM speed, poor lubrication when drilling hard metals, it can destroy those double-sharpened HSS-G drill bits. The word precision actually translates that the hole it would be 100% centered and that it is immediately usable (clean cut) for mounting your part to it.
Therefore those HSS-G they do boost productivity and they do what they promise.
Havera & Bosch HSS-G drill bits are actually the same, my selection was mostly based in the local availability and also pricing.
About pricing for its one drill bit, just multiply the mm (dimension) by one EUR, the largest 10mm is priced between 7.60 to 9.50EUR.
I did manage to cut it in half and this is how I learned the price.
Below is a set of pictures for your information.
The chart about RPM VS drill bit dimensions is something which I have print and is hanging over my wall as life time reference.
Regarding drill bit lubrication, a good friend of my machinist, gave me one solution which containing special oil and water, which is the actual stuff that they use in metal lathe. Therefore if you follow all those notes and warnings, your HSS-G drill bits will do the rest for many years to come.