WinterSilks Silk balaclava: breathes, fits under helmet, non-absorbant,
another variation for colder days by itself, covers ears and face, warms air when mouth breathing.
Breathable, waterproof
J&G Cycle wear helmet cover for warmer times, blocks wind.
Both for coldest times.
JC Penny 4 in 1 hood REALLY WARM, haven't tried it for fit under a helmet, it's definitely thicker than the silk balaclava.