What Our Gearhead(R) Experts Are Saying:"I wore this on a hilly trail run where my effort swung between easy jogging and full sprints up short climbs. The eyelet mesh panels kept me from overheating on the hard pushes, and the thumb loops kept my sleeves out of the way the entire run."A trail run with constant surges, easy stretches followed by short, punishing climbs, needs a layer built to keep pace with effort that never stays steady for long. The ZoneKnit Crewe from Icebreaker handles that unpredictability well, with zoned merino construction that channels heat away from the body right where exertion spikes hardest. Eyelet mesh panels add breathability without giving up warmth on the easier miles, while a gusset underneath keeps full mobility through every stride and arm swing. Thumb loops hold sleeves in place through repetitive motion, and raglan sleeves paired with flatlock seams cut down on friction over the length of a long run. A drop-tail hem adds coverage without ever getting in the way.