Home / Special Content / Seamless Down Hugger

Seamless Down Hugger

To prevent down from shifting and producing cold spots, sleeping bags have been traditionally made with inner walls called baffles. The Seamless Down Hugger series is the world's first sleeping bag to remove the traditional baffles. This radical construction technique produces a sleeping bag with a single, continuous chamber and allows the down to loft to its fullest potential. This technique doesn't affect the lightweight and compact nature that Montbell's sleeping bags have become known for. The next generation of sleeping bag is here!

A Eureka Moment: Eliminating the Baffles

We asked ourselves, "Is there anything we can do to improve down's ability to insulate?" As ideas were being tossed around, one idea that came up was, by eliminating the baffles the down would be unhindered and each down ball could loft/puff out to its fullest ability. This extra volume of air trapping down would thereby increase the insulative properties of the bag. However, the catch is baffles prevent down from shifting out of place. When down shifts out of place, cold spots can form. This is when there is a spot in the sleeping bag that has no down coverage.

If baffles prevent cold spots, how does eliminating them improve warmth?

Our first reasoning was that if you give down more room to loft, we increase the layer of trapped air and we can improve the insulating performance of the down. Another reason, since sewing baffles into the sleeping bag creates holes in the outer fabric, the sewing holes are ways for warm air to escape. By eliminating most of the sewing lines on the bag, we are able to trap more air. However, in order to make our idea a reality, we have to remove the baffles and come up with a way that could hold the down in place. This was the biggest hurdle we faced when trying to reach that next step.

Spider Yarn: a specialized thread that entangles down

When looking for a suitable baffle replacement we received a little inspiration from nature, the spider. The thought was, "If we could make a web inside the sleeping bag, it could suspend the down and hold it in place, keeping the down from shifting." Based on this initial concept, work began on developing a specialized thread that could trap and hold down. Calling this new thread "Spider Yarn," we were successfully able to suspend a layer of down throughout the entire bag. This new construction is the "Spider Baffle System."

Excellent stretch to provide better sleep

The Spiral Stretch System (US.Patent No.7,900,301) is what made Montbell sleeping bags famous. The ability of the bag to move with you during the night has provided comfort for many. The Seamless Down Huggers are no different. Although the exterior of the bag is a solid piece of fabric, the interior of the bag features a combination of the fabric's mechanical stretch and elastic stitching. The result, the sleeping bag hugs and moves with you as you sleep, but doesn't feel restrictive. This also means that as you move, gaps between you and the sleeping bag are less likely to form and maintains even coverage of the sleeping bag, maintaining your warmth.

900FP High Quality Down

The Seamless Down Hugger Series utilizes some of the highest quality down available. Since high quality down is generally larger in size, we can use less down by weight and achieve the same thermal profile compared to using lower quality down. This makes the sleeping bag lighter and more compact compared to the same sleeping bag made with lower quality down. Higher quality down is able to recover its loft much quicker than lower quality down.

Ultralight Fabric

This ultra thin, lightweight fabric is strong for its weight. Because each individual thread is super thin and supple, the fabric is so light that it creates little resistance, allowing the down to fully loft.

By combining the Spider Baffle System with a weatherproof breathable material, we've created a sleeping bag that maximizes down's ability to insulate. By seam sealing, we are able to effectively shut out water, keeping the down dry. We envision usage of this model in humid and wetter climates, especially when condensation on the interior of your shelter could compromise the down's ability to loft.


Superior breathability and weatherproofing

The bag keeps the down dry through exceptional weather and wind proofing to shut out the elements while releasing water vapor produced by your body while you sleep due to the materials superior breathability.

Shuts out water

Shuts out water penetration along the zipper. The Aqua-Tect Zipper makes the zipper easy to use and reduces weight by eliminating the need for a weather flap that would cover and protect the zipper from water entry.

Our state-of-the-art sleeping bag design achieves cutting edge performance without adding extra weight. The baffle-less outer design allows for unrestricted loft while the interior elasticized stitching pulls the bag closer to the body without making you feel constricted. Sleeping in the backcountry has never felt so good.

Seamless Down Hugger 800 Half Length

These half-length bags allow you to combine your puffy jacket with your sleep system, cutting down your trail weight even further.

Tapered Spiral Stuff Sack

Utilizes the same bias cut fabric used for our Spiral Stretch System. Because the fabric stretches, it's possible to alter the shape of the sleeping bag to some degree so it fits in the available space of your backpack. The opening to the stuff sack is wider to enable easier stuffing.

Storage sack doubles as a laundry bag

When not in use, the sleeping bag can be stored loosely in this storage sack to preserve the down's ability to loft. The storage sack also doubles as a laundry bag for the sleeping bag. Down's ability to maintain its loft is tied to how clean it is maintained. The oils that the body naturally produces can sometimes affect the lofting properties of down. So if you start to notice that the down isn't loft like it used to when first purchased, it may be time to open the User's Manual and follow the washing instructions.

Sleeping Bag Guide