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Say goodbye to midwinter chills. Relance™ Primeflex and PeakFill™ Active Insulation combine in this fully articulated, warm and highly breathable active insulation midlayer.

Stand up to the most daunting weather reports and midwinter chills with our Fernos Insulated Pant. This reliably warm and highly breathable insulation midlayer laughs off sub zero days with a Relance™ Primeflex shell and PeakFill™ Active Insulation. The medium cut is designed for an on-the-go lifestyle, be it a pick-up pond hockey game or chasing the kids up the trail. Stretch panels and full articulation allow for complete freedom of movement while thoughtful design details like an encased elastic waistband, zip fly and drawcord make for easy on and off—although the Fernos is the type of insulated comfort you won't want to shed anytime soon.

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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 PeakFillActive 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
  • Stio PeakFill™ Active Insulated layer with stretch panels and articulation for full range of motion
  • Microfiber with soft hand and mechanical stretch
  • Encased elastic waistband plus zip fly and button closure with drawcord for easy on and off
  • Custom Stio® drawcord for customized fit
  • Reach-in hand pockets
Weight and Measurements
  • Weight: 10 oz.
  • Inseam: 29 1/2"
Other Details
  • Heat transfer Stio® and Pinecone logos
  • Imported
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