In the fall, when temperatures swing like a bipolar monkey on meth, a good base layer is paramount. Sherpa Adventure Gear’s Vayu Long-Sleeve Crew fits the bill, breathing during the heat of day and insulating through the cold of dawn and dusk. The Vayu’s PreMerino fabric, a 50-50 blend of PrimaLoft and Merino wool, creates a soft, supple, quick-drying shirt that also resists manky microbial growth—a must during hunting season, when clothes only get washed after a kill (and then, only maybe). Throw in a performance fit and microdenier-joined seams for reduced chafing, and you’ve got a solid shirt for every fall outing, from trail-running to backpacking and everything in between. $89; sherpaadventuregear.com.