Mountain Hardwear’s New StretchDown Puffy Is Designed Durable for Movement

What Is StretchDown?

We love a packable, ultralight down jacket, and they have their place, but relying on one for all outdoor pursuits has its drawbacks. They can be easy to tear and susceptible to abrasion, and often utilize larger baffles to save weight, which can lead to down migration. These jackets also generally have no stretch, which isn’t always conducive to taking on complex bouldering problems, navigating overgrown trails, or squatting over the camp stove.

That's fine if you’re packing your puffy as a backup layer for downtime or heading out on an adventure with few branches and brambles, but it isn’t always the most practical in challenging outdoor environments. StretchDown is Mountain Hardwear’s solution to these problems. The series is designed for hard efforts in cold temperatures where movement and durability are paramount.

StretchDown jackets' fabric is tougher; they use a 20-denier face fabric, compared to the 10-denier fabric used for the brand’s popular ultralight Ghost Whisperer jacket. It's made of nylon blended with elastane to allow for stretch and freedom of movement. StretchDown also has a PFAS-free DWR coating to keep you dry in light precipitation, preventing unwanted down clumping when the weather turns. For the update, The Nut also opted for a face fabric with a tighter weave that prevents down feathers from poking through.

Where StretchDown really stands out, though, is its ability to hold its 750-fill RDS-certified down insulation in place.

Holding It Down

A down jacket is pretty useless if its down insulation doesn’t stay evenly distributed. This latest StretchDown update, according to the brand, will lower down migration by up to 60% over previous versions. To do this, they use two proprietary, space-age-sounding technologies: Doppleweave and Cohesion Insulation Interlock. During my visit to HQ, Ruth Beatty, MHW's design director, and Megan Duffy, product line manager for outerwear, walked us through the entire line to show how the new tech works, from the fabric construction to the finished product.

Most down jackets use thread to create the baffles that hold the down fill in place. This method works, but is prone to unraveling and doesn’t allow for any stretch or movement. Taking a different approach, MHW's team came up with a design in which the fabric is woven together, not stitched, which creates continuous zig-zag baffles and joins that cannot come apart. The design allows the stretchy fabric to move with the wearer without putting strain on the baffle structure. This is Doppleweave.

The Doppleweave construction allows for discontinuous baffle joins, meaning that within each individual join, there are small gaps that function as nets to catch the fluffy parts of the down feathers, holding them in place. Once a few feathers are caught in the gaps, the fill starts to attach to itself, creating evenly spaced concentrations of down that span the entire garment. This is Cohesion Insulation Interlock.

Working together, the two create a stretchy jacket that provides consistent, even warmth and moves in all directions without fear of tears or threads coming undone.

A More Versatile Puffy

Down jackets aren’t cheap, so in an ideal world, the one you buy isn't just for outdoor adventures. StretchDown can hold its own in the wild, but it's also an understated option that looks great for everyday wear too. The face fabric isn't just tougher than before; it's also softer and less crinkly. And its matte appearance doesn’t look quite so straight-off-the-trail as many other down jackets do. While GORP's moment seems like it'll never end, it’s nice to have a jacket that transitions into daily life with a little less flash.

The DWR finish I mentioned earlier won’t keep you from getting soaked in a downpour, but it does well on misty, foggy days. StretchDown also comes in a variety of baffle sizes and silhouettes, which means you can find the exact option for your needs (or style). The light baffle version is ideal for high-output activities like hiking, climbing, or cycling; the medium baffle is the Goldilocks middle ground that straddles the line between performance and comfort; and the big baffle is designed for trudging through a sub-zero commute or as an outer layer on the slopes.

Early Impressions of Mountain Hardwear StretchDown

It was August when I tested out the new StretchDown, but we were in the Bay Area, a place with famously cold summers (we’ve all heard the Mark Twain quote). The light baffle was clutch on the early-morning ferry ride from downtown San Francisco to Richmond, where fog, wind, and high speeds combined to give us the perfect testing conditions on the ferry’s upper deck. After our day in the office, we took medium baffle jackets for a winding hike through the towering old-growth redwoods of Muir Woods, where the trails spit us out at Muir Beach as the sun dipped below the horizon that evening. After a dip in the Pacific, the medium baffle went straight on and stayed there for the next couple of hours, until a quick detour on the way back to the hotel, where we gave the big baffle jacket and StretchDown pants a quick test on the cliffs along Highway 1, putting them up against the fog and wind that had rolled in. Since we didn’t get a lot of time with the big baffle that night, I’m looking forward to rocking it in the mountains this winter.

The stretch is comfortable and forgiving, and while they’re not the most packable down layers I’ve ever used, they aren't a burden when packed away during a day hike, especially the light and medium baffle versions. The big baffle is a layer I'd reserve for very cold days, though—I wouldn't plan on stuffing it into a pack if I can help it. The face fabric is surprisingly soft, and I appreciate that I don’t feel like I need to be precious with it, especially after tearing through—literally—a few of my favorite down jackets over the years.

Now I just need temperatures to drop.

LEARN MORE ABOUT STRETCHDOWN