BarvazI've never seen synthetic insulation advertised as "down", so I'm sure this has feathers. I don't know enough to say whether it's more likely that this has goose or duck down, though. (I typically prefer synthetic insulation materials anyway.)
MountainPassI've started to see a few companies (Marmot comes to mind) and reviewers call it "synthetic down". It's not common, but maybe it's something that brands are pushing for with new advancements in synthetic insulation . . . or maybe it's just a marketing push.