Step drill bits (where to get) ?

[Gytis]

Is this for counterboring caphead bolts? If so, why not use a proper counterbore?

Counterbores - Arc Euro Trade
7PC SOCKET CAP SCREW COUNTER BORES COUNTERBORE | eBay

Hi birchi,
yes, for cap head bolts, Thanks for the links!
I've seen these drill bits, but I was not sure about them, since I'm a carpenter, so was looking for something similar to my tools

Thanks