Designed as a base layer for Himalayan expeditions the I3 micro fleece has a TOG rating equivalent to a 3 TOG eiderdown. It is so nice and toasty to wear and has a lovely soft feel to it. It can be worn as a warm base layer or as a mid layer or even just for lazing about in. Over a base layer it is ideal for through the night sailing, keeping you nice and toasty all night long.
Undoubtedly the best bit of kit I own.