Mystic UL 15°

Down fill Big Agnes System bags designed to excel in all conditions and provide more room than a mummy bag

Down fill Big Agnes System bags designed to excel in all conditions and provide more room than a mummy bag

The Mystic UL 15 is one of our most technically designed Big Agnes System bags, using our full pad sleeve design, a very durable nylon rip-stop shell fabric, and super cozy 850 fill power DownTek™ water repellent insulation. This bag combines ultralight versatility with a long line of packable creature comforts. Whether you’re a 3/4 length-pad-carrying, fast fly tent-gram-counter or just gearing up for a trip where weight and packed size is important, this is the go-to bag for you.
$379.95 to $429.95
100% Guarantee


Our top priority is to provide customer service as stellar as the award-winning products we create. If one of our products does not perform to your satisfaction, contact our customer service team and we will help you find gear that fits your needs.
$379.95 to $429.95

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Specs + Sizing

Bag WeightSmall: 1lb 15oz / 879g / Reg: 2lb 2oz / 964g / Long: 2lb 5oz / 1.05kg
Fill WeightSmall: 12oz / 340g / Reg: 14oz / 450g / Long: 16oz / 451g
Compressed Bag SizeSmall: 6in x 6.5in / 15 x 17cm / Reg: 7in x 7.5in / 18 x 19cm / Long: 7in x 7.5in / 18 x 19cm
Stuff Sack SizeSmall: 8in x 17.5in / 20 x 44 c/ Reg: 8in x 17.5in / 20 x 44 cm / Long: 8in x 17.5in / 20 x 44 cm


Design improves connection between pad sleeve and bag providing a roomier sleeping space without adding bulk

Sculpted contour allows the bag to drape around you, increasing insulation performance

Free Range Hood design gives you the freedom to lift your head while snuggled in the hood

Low profile cordlock lets you un-cinch the hood with one hand

Stretch fabric panel beneath hood creates a designated pillow pocket

DownTek™ water repellent down repels water while maintaining insulating value

Zipper Garage

Mate together left and right zip bags

No-draft collar, No-draft wedge, No-draft zipper

Interior fabric loops for sleeping bag liners

Exterior loops for hang drying or storage

Mesh storage sack & nylon stuff sack

Construction + Materials

Superlight Nylon rip-stop shell fabric with high tear strength and a water repellent finish 

Nylon Taffeta lining

Insotect Flow™ construction

Tapered vaulted foot box creates wiggle room for your feet with out creating large cold air pockets 

850 fill DownTek™ water repellent down

Integrated full pad sleeve

Rectangular shaped bag

70" / 178cm YKK #5

Here’s what other people think.

What’s in a Name?

In 1901, the town site of Mystic was named by Fred May, a settler and rancher, after his boyhood home in Mystic, Iowa. Mystic was located at the head of Trull Creek, beyond the head of the Sleeping Giant. The Elk Mountain School operated there from 1911 to 1942. Now the land is literally nothing but a crossroads to the west of Steamboat Springs. It’s home to a cattle ranch, the occasional tumbleweed, and the whispers of the pioneers who once lived there.