I have a good balaclava - but my head is so big that it leaves a gap on my neck. Bought a winter neck gaitor but it's too heavy - I just need something thin to cover the gap. I'm on a mission to find my perfect non-sweat winter setup.

It's hard to beat a wool Buff.

Polar-tech fleece

The cheap one is cut so it rolls up rather than stay flatter, Patagonia's does Not.

I second this. Most useful item of winter clothing in my quiver.