Merino wool fibers are measured in microns, millionths of a meter. The thinner the fiber, the softer the feel, and the Icebreaker Shifter Long Sleeve Hoodie hits right at the perfect weight for an all-day active midlayer. The cut is hoodie-like, but it's not thick or overly baggy, so it's a perfect California hoodie and insulation under a shell. Space robots can keep pumping out new synthetics, but they've yet to match Merino for softness, insulation, odor, and moisture-management!