This is technically a mid-layer but it's light enough to be worn as a base layer and feels super soft and snug, so if you prefer a thicker fabric against your skin, especially in very cold conditions, the Micro Pulse may work for you. And you can't quibble with the price.
The Zetland 100 Micro Fleece fabric is both wickable and breathable with a good warmth to weight ratio, and the fleece's flatlock seams add to the comfort factor, whilst the half-zip and slight scooped back are nice touches - especially on a garment at this price.