Big Agnes Bellyache Mountain SL 17

Traditional mummy bags are built for performance. In its first diversion from the Big Agnes System Big Agnes introduces the most technical old-school sleeping bags ever. These bags are insulated with DownTek water repellent down and constructed with Insotect Flow patented technology. Their mummy shape and lightweight materials will get you wherever you want to go, fast and dry.



With the Bellyache Mountain SL 17, Big Agnes introduces a Traditional Mummy down sleeping bag line featuring DownTek 0 water repellent down. DownTek 0 transforms down into a water repellent, anti-microbial and anti-bacterial insulation material. Even in the wettest of conditions, DownTek 0™ repels water while maintaining loft, insulation value, and breathability.

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  • Traditional style mummy shaped bags designed without the integrated pad sleeve
  • 70″/178cm YKK #8 zipper
  • Interior fabric loops for sleeping bag liners
  • Mate together left and right zip bags
  • Mesh storage sack & nylon stuff sack
  • No-draft collar seals around neck to keep cold air from sneaking in
  • No-draft zipper tube insulates along the length of the zipper
  • Flow™ Construction: Insotect Flow™ is a flow-optimized insulation system that delivers uniform heat distribution and natural body contouring through its revolutionary baffle design. Flow Construction eliminates lateral and vertical down shifting by using vertical chambers with Flow Gates to regulate fill positioning and density. Strategically placed Flow Gates minimize vertical down shifting while vertical chambers minimize lateral shifting. With continuous vertical Flow chambers in place of traditional side seams, Flow bags eliminate potential cold spots which can occur with side seams. Vertical baffles now flow with your body for more rapid and uniform body heat distribution.
  • When you are in the bag, on your back, the right zip will be on your right side, left zip on your left side


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