Just got the one in continuity’s link from Sportspursuit. That one is indeed the lightest of Pertex grades great for a stuff in pack wind breaker/cool evening jacket.
Wouldnt wear that one through autumn to spring even with additional layers underneath, its defeating its purpose.
I think if you could find it at the right price the Rab Vapour rise lite alpine would be good. Little more insulation than the one above but still light enough to work with layering. But size up they (due to the cut) come out small.
This one