The Patagonia R1 Jacket is built for the aerobic middle ground, the sustained effort where a midweight fleece traps too much heat and a baselayer alone isn't enough. The Polartec Power Grid construction uses a textured grid on the interior to push moisture off the skin and circulate air, keeping output high without the clammy buildup that kills a cold-weather climb. On multi-day approaches where laundry isn't an option, the HeiQ Pure anti-odor treatment and the grid's fast-drying structure work together to keep the jacket in rotation through back-to-back days. What Our Gearhead(R) Experts Are Saying:"I wear this on the approach when I'm moving hard enough that a heavier fleece would have me soaked. The grid construction vents heat before it builds up, so I stay dry through the crux of the climb."