Whether we are pushing up the skin track or out for an early morning hike, wintertime adventures start with the Backcountry Pines Microgrid Ultra - Lt Baselayer 1 / 4 - Zip Top. Through extensive Gearhead testing, we developed this top to regulate our temperature and wick away moisture from our skin to keep us more comfortable in cooler temperatures. The ultralight design ensures we aren't weighted down, while the brushed polyester fleece interior keeps us warm and allows our bodies to breathe.