BaaBaa Merino Skullcap
What MTB Review
"This thin but luxuriously warm cap fits neatly under a helmet to warm the bonce while wind whips through the helment vents."
Cycling Weekly Review
"Despite being thin enough to barely notice its presence, the five per cent Lycra content means it has kept its shape even when sodden. It's warm down to 6°C or so and has become our default skullcap unless its 'pure free-zunn'.