The Patagonia Men’s R1 Thermal Bottoms are technical fleece pants designed as an insulating midlayer for cold-weather mountain activities. Built for alpine environments and high-output movement, they combine breathable warmth with stretch mobility, making them suitable for activities such as climbing, ski touring, winter hiking, and mountaineering. The bottoms are made from Technostretch fleece, a stretch-woven fabric composed of approximately 91% recycled polyester and 9% elastane. The exterior face is smooth and durable, helping resist wind and light snow, while the interior features a micro-grid fleece backing that traps warmth while efficiently wicking moisture away from the skin. This construction helps regulate temperature during active use by balancing insulation with breathability. The stretch fabric and articulated construction allow unrestricted movement during technical terrain or steep climbs. A low-profile waistband with an internal drawcord provides an adjustable fit that layers comfortably under harnesses or outer shell pants. The slim, tapered legs improve visibility of foot placement and make the garment easier to layer under ski or mountaineering shells. Additional features include zippered hand pockets for storing small essentials and a streamlined design that minimizes bulk under outer layers. Manufactured in a Fair Trade Certified™ factory, the R1 Thermal Bottoms reflect Patagonia’s focus on durable performance apparel with responsible production practices.

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