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Make the most of your winter's athletic pursuits. Relance™ Primeflex and PeakFill™ Active Insulation come together in this pant's dynamic, well-articulated fit that hugs warmth in and keeps cold out.

Inspired by our popular Knicker style, the Fernos Insulated Pant makes its debut as your go-to layer for cold weather cardio, with a large dose of comfort. Whether you're taking a snowy winter run, stacking firewood at the yurt or layering up around a campfire, you'll love these pants for their reliable warmth and undeniable comfort. The soft Relance™ Primeflex shell is paired with PeakFill™ Active Insulation and 50% recycled polyester to guarantee maximum breathability and warmth. Stretch panels and articulation allow you to move freely, and an encased elastic waistband makes these cozy favorites easy to slide on and off if you need to transition throughout the day.

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 Image Relance™ Primeflex
 Image PeakFill™ Active
Shell and Lining

Relance™ Primeflex, 50 Denier Microfiber Mechanical Stretch Plainweave, 100% Polyester,  85g/m2 with 80/20 DWR finish

Relance™ Primeflex 100% polyester microfiber offers better drape and wicking than that of normal polyester fibers. This fabric features a soft hand, comfortable stretch, wind resistance, and excellent resiliency and strength.


PeakFill™ Active Insulation, 50% Polyester, 50% Recycled Polyester, 40g/m2

Our PeakFill Active proprietary insulation balances warmth and breathability to maintain lasting athletic comfort across the entire conditional range. Designed to keep core temps regulated, the synthetic fiber fill draws on a spiral filament structure to enable greater stretch, faster recovery and quicker dry times than traditional lofted insulation whether rolling slow at valley level or working hard up in the alpine.

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Climate Neutral

We completely offset the footprint of each order through our commitment to being climate neutral. As part of our mission we value being good caretakers of the mountain life and protecting the places where we play.


We are committed to building garments that are durable, timeless and continue to perform season after season. Over 50% of our product line incorporates preferred materials, which include organic cotton, recycled materials and responsibly-sourced down. We are committed to growing our preferred materials usage to 75% by 2025.

Trade-In Program

We believe a circular commerce system will design out waste and pollution, allowing for used clothing to be renewed and put back into use. Stio Second Turn™️ is our gear renewal program that allows customers to trade in and shop used apparel.

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Fabric Details
  • PeakFill™ Active Insulated layer with stretch panels and articulation for full range of motion
  • Microfiber with soft hand and mechanical stretch
  • Encased elastic waistband for easy on and off
  • Custom Stio® drawcord for customized fit
  • Reach-in hand pockets
  • YKK® zippered thigh security pocket
Weight and Measurements
  • Weight: 12.31 oz.
  • Inseam: 28 1/2"
Other Details
  • Heat transfer Stio® and Pinecone logos
  • Imported
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