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Introduced in 2009, MontBell's Spiral technology is an alternative way to create a stretchy sleeping bag and save some weight to boot. The Spiral technology is best described in their own words: "By integrating a woven fabric 'cut on the bias' and orienting the fabric's warp and weft threads at 45 degrees to major seam lines, the sleeping bag becomes more fluid or elastic in nature. Additionally, 'spring like' crimped fibers are used in the weave of the fabric to capitalize on their inherent stretch properties." Rather than the traditional horizontal or vertical orientation of the down tubes, they are oriented on a 45 degree angle and appear to spiral around the sleeping bag.

For 2010, MontBell has extended their Spiral Stretch technology to their entire line of sleeping bags. Thus the former "UL Super Stretch Down Hugger #3" is now the "UL Super Spiral Down Hugger #3." That's a mouthful, but it is descriptive. Whereas the previously reviewed MontBell UL Spiral Down Hugger #3 uses only the Spiral Stretch technology, the MontBell UL Super Spiral Down Hugger #3 (reviewed here) is a combination of the new Spiral Stretch technology plus the original Super Stretch technology (elastic stitching in the seams to create small "gathers" in the quilting), which allows the bag to contract and expand even more. So what are the differences between these two bags, and are these differences meaningful for backpacking?


  • Introduction
  • Description
  • Performance
  • Comparisons
  • Assessment
  • Specifications and Features

# WORDS: 1970

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