Sierra Designs Foxboro Sweater Knit Jacket review: a stylish mid or outer layer, but for light duties only

Comfortable and versatile, the Sierra Designs Foxboro Sweater Knit Jacket is a zip-up that can be worn as an outer layer or mid layer

Sierra Designs Foxboro Sweater Knit Jacket
(Image: © Kim Fuller)

Advnture Verdict

The Sierra Designs Foxboro Sweater Knit Jacket is ideal for travel because of its comfort levels and versatility. It would not be my first choice as a technical mid layer or outer layer on big outdoor adventures, but as a more casual piece it checks the boxes of a comfortable and flattering fit while also taking the chill off.


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    Long length for more coverage

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    Midweight, sweater knit fleece can be an outer layer or insulating mid layer

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    Classic look paired with technical features

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    Zipper garage on stand-up collar to prevent chin chaffing

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    Laminated and zippered hand and sleeve pockets


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    More relaxed fit can make a top layer harder to fit over it

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    Heavy sweat in this sweater jacket can leave residual odor

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Sierra Designs Foxboro Sweater Knit Jacket: first impressions

I first tested the Sierra Designs Foxboro Sweater Knit Jacket (available direct from Sierra Designs) in a women’s medium size, but quickly realized the piece has a generous fit for a fleece jacket, so swapped down. The small size still has a relaxed fit, but that’s how it’s designed to be. The style runs a little longer, meaning more coverage and warmth. 


• List price: $99 (US) / £99 (UK)
• Fabric: 100% polyester brushed back heathered technical fleece
• Gender availability: Men’s and Women’s
• Sizes: Women’s: XS-XL; Men’s: S-2XL
• Weight (Women’s medium): 500g / 8.83oz
• Colors: Women’s: Windsor Wine / Ensign Blue / Gun Metal; Men’s: Gun Metal / Midnight Navy / Ensign Blue

This sweater jacket is ideal as a comfort layer, whether that’s as a mid layer underneath a larger jacket on extra cold winter days, or as an outer layer on more temperate days in the spring and fall months. A zipper garage on the main zip-up ensures protection from chin chaffing, and zippered hand and sleeve pockets are lined with lamination to ensure valuables are extra secure. 

While the technical fleece of the Sierra Designs Foxboro Sweater Knit Jacket can hold up to more adventurous outdoor efforts, the piece really seems made as a casual comfort layer.

Sierra Designs Foxboro Sweater Knit Jacket: in the field

I brought the Sierra Designs Foxboro Sweater Knit Jacket on a recent winter visit to Minnesota. I live in the Colorado mountains and I’m no stranger to chilly temps, but there’s something extra bone-chilling with the more humid air and frigid wind in America’s Midwest that can cut right through you. This sweater jacket was an ideal layer to have along from the car ride and plane trip there and back, and it was a cozy zip-up to have while relaxing, and as a mid layer when out and about.

Sierra Designs Foxboro Sweater Knit Jacket

This sweater jacket is lovely and soft on the inside but the outer fleece is tough enough to take some punishment (Image credit: Kim Fuller)

The next-to-skin fleece on the inside of the Sierra Designs Foxboro Sweater Knit Jacket is super soft, while the outer fleece has a more technical finish that makes it more durable and offers some wind shield. The fit of the fleece is more relaxed, and while this was ideal as a comfort piece during vacation, it’s a bit of a larger and looser mid layer so keep that in mind if you’re wearing a jacket over it. Definitely size down if you want to have a more snug fit, but the sweater jacket is designed to give some room.

The hand and sleeve pockets on the sweater jacket have a laminated border around the zippers. This is great for durability and protection of your essentials, but the lamination seems to take away from the style versatility of the piece, making it more technical looking than fashion-forward. The main zipper is sturdy, and I like that my chin is protection from chaffing by the zipper garage on the stand-up collar.

I’ve mostly tested the Sierra Designs Foxboro Sweater Knit while relaxing and on to-and-from occasions, but the little time I have moved a little more rigorously in it and gotten warm enough to perspire, I notice the fleece material will hold onto odors until it’s washed.

Kim Fuller
Advnture contributor

Kim Fuller is the co-founder of Jaunt Media Collective based in Vail, Colorado. Jaunt’s family of print and digital magazines includes YOGA + Life, Spoke+Blossom and Covered Bridge. Kim started her career in media as a freelance journalist and has contributed to a number of national and regional publications, including Elevation Outdoors, 5280 Magazine, The Denver Post, Outside, Advnture, Gear Institute, SELF Magazine, Wanderlust Journal and The Infatuation. Kim spends most out-of-office hours seeking sunshine and singletrack, teaching yoga around town, dining with friends or planning her next adventure. Stay connected through @lifeinfull on Instagram and scope the mags at