"I realise I am no expert but I have been drilling holes in things for several decades. I accept that drill bits snap occasionally but this one went within 1 sec of first use.
I had already drilled a hole with a 3.5mm bit but I needed it a little bigger so I used the new 4mm bit. It snapped almost instantly although not quickly enough to not get itself jammed in the hole. Rather than speeding things up, I then had to drill 2 completely new holes because I couldn't remove the broken drill bit.
I have since used the 3mm bit without any problems so hopefully the rest of the bits will also be ok.
For the price, I can't be bothered to complain and I will just buy a replacement 4mm.
Still, it is very annoying and the reason why I cannot recommend this drill bit set."