The GripGrab Merino Bamboo 1/2 Zip Long Sleeve Base Layer is the height of luxury winter layering. The unique two layer fabric combines a merino wool outer with a bamboo inner, to create a super soft, incredibly breathable, and highly insulating baselayer. The two natural fabrics are known for their outstanding temperature regulation and wicking performance, so they will keep you comfortable even when you are working hard in the winter months. The turtle neck collar provides extra warmth and protection, but when you do need to 'vent out' the 1/2 length zipper makes it easy to encourage airflow through the layers. Thumb holes are great for keeping the base layer in place when putting on your other layers. This is your secret weapon for those winter bike rides and all kinds of winter activities during the cold months.