Behind the switch, two way switch (EU) with Shelly 1

I want to connect Shelly 1 to multiple two way switches but I can't find the correct schema in lexicon for this wiring I have behind the switch. Any suggestions?

Here's the switch (BTicino Classia):

Brown wires go to I and L, blue goes to N, that's clear. But which one goes to O and SW ? Black to O and gray to SW?

I have neutral wire (blue) in the junction box where switch, pictured above, is located.