Ah I have one of those! Somewhere! When I bought my first helmet and was paranoid about tearing my ears off the guy said "have this," and then thought, "fucksake I hope he leaves my shop that probably won't exist in ten years time."
I've used it once. But now you mention winter, and I recall I get cold on the flipping motorway in the head zone, so maybe I'll have a look for it again.