E.C.W. Low Profile Fleece Watchcap

•  Constructed of  7-ounce Blizzard Fleece™
•  Offers dry comfort and substantial warmth without the
    itching and irritation associated with wool or poly/cotton 
    watch caps
•  Low-profile design fits easily under helmets
•  Wear inside out to avoid seam irritation when wearing a
    helmet

I love these!!!!

They don't provide much of a description of these on the Blackhawk web site so I guess it's up to me.  On some products if they don't say anything then nether do I.  On this one I had to.  I have had a bunch of these.  The reason I say a bunch is because they are so nice that mine get taken by friends, the Wife who uses it during running in cold weather, my kid going to school during the winter.  These were developed by the Ancient Spartans for use under their Helmets in 500 BC.  I could be wrong on that last thing but I'm not wrong that is a great item and you won't go wrong with it.