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  • Big Agnes - Mystic UL Sleeping Bag: 15 Degree Down - Blue
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  • Big Agnes - Mystic UL Sleeping Bag: 15 Degree Down - Blue

Big Agnes Mystic UL Sleeping Bag: 15 Degree Down

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    5 Reviews


    Slide into the Mystic.

    Put on some music before turning in and catching some refreshing sleep with the Big Agnes Mystic UL 15 Degree Down Sleeping Bag. It has plenty of warmth for three-season backpacking trips and will also crush it on winter hut or yurt trips. The Mystic ditches bottom insulation in favor of an integrated pad sleeve, which saves on weight and boosts warmth. As a result, the Mystic weighs less than 2.5 pounds. Don't think for a second that it sacrifices warmth, though—it's loaded up with 850-fill DownTek water-repellent down that's arranged in Insotect Flow vertical baffles. The baffles conform to your body for increased warmth and comfort and use internal gates to keep the down in place so you don't have to deal with cold spots.

    Not only is the down water-repellent, but the Pertex ripstop nylon fabric is so tightly woven that it prevents moisture, like tent condensation, from seeping in. The rectangular shape means you have a few sleep-position options. Drafts tremble in fear before the Mystic thanks to the no-draft collar, wedge, and zipper that keep them locked out and your heat locked in. And, as a final touch, Big Agnes designed the Mystic so that left-zip bags can connect to right-zip options, letting you and all your stuffed animals sleep together comfortably.

    • Toasty, lightweight, weather-protective adventure bag
    • Water-repellent fabric helps protect you from elements
    • Hydrophobic 850-fill down insulation stays warm when wet
    • Pad retainer design shaves weight and locks in your bed
    • Flow vertical baffles help keep heat in the right spot
    • Draft collar shields you from nasty gusts
    • Big Agnes is based out of Steamboat, CO
    • Item #BAG00A1

    Tech Specs

    [shell] Pertex nylon ripstop, DWR, [lining] nylon taffeta
    850-fill DownTek
    Max User Height
    [regular] 5ft 10in, [long] 6ft 6in
    Shoulder Circumference
    [regular] 69in, [long] 72in
    Hip Circumference
    [regular] 63in, [long] 66in
    Foot Circumference
    Draft Tube
    Fill Weight
    [regular] 12oz, [long] 14oz
    Stuff Sack
    Stuff Size
    8 x 17.5in
    Claimed Weight
    [regular] 2lb 7oz, [long] 2lb 11oz
    Recommended Use
    camping, backpacking
    Manufacturer Warranty

    Tech Specs

    • Reviews
    • Q & A

    What do you think about this product?

    Have questions about this product?

    Side Sleepers Rejoice!

    • Familiarity: I've put it through the wringer

    This warm sleeping bag/ sleep system is my new favorite way to enjoy sleeping in the backcountry. I recently bought this bag along with the BA sleeping pad that goes with it and was amazed at how comfortable I was able to get. I am a side sleeper and find myself tossing and turning all night. This bag allowed me to always stay warm and on top of my sleeping bag.
    I took this bag on a seven day backpacking trip through the superstitions located in east central AZ. The lightweight design pairs with the compressibility to make it and easy choice for backpacking. When the nights got cold, as low as 20 degrees, I stayed pretty warm. I pair this with the big agnes liner and stay toasty on the coldest nights.
    I am a tall guy, 6'3", and have some pretty wide shoulders. I found this bag to fit me well when I bought the long version. It is roomy for a mummy bag and I enjoyed this. I will be a long time user of the sleep system bags from Big Agnes.I am excited to bring this bag on my next 17 day hike.


    • Familiarity: I've used it once or twice and have initial impressions

    This sleeping bag kept me super warm on a 25 degree night when I was staying in a yurt. At first, the yurt was cold and it kept me super warm! Once it was heated up, I slept with the bag unzipped and it was perfect then as well!

    This sleeping bag is also super light! We hiked (skinned) to the yurt and carried all of our gear, so having a light down bag that compresses well was key. This helped me keep my bag in a reasonable weight, while also being warm enough.

    The shape of the bag is wider than my other bags, which was nice to have the extra space! It has a feature to attach to a Big Agnes sleeping pad as well, which would keep the bag in place as you move within and prevent it from twisting. Between that, the warmth, and the packability, I highly recommend this bag!

    Perfect Bag

    • Familiarity: I've used it several times

    I bought this so I could stay toasty and not fall off my pad. I slept like a baby. The downside is that big agnes hasn't fully figure out their system bags. Where the bag connects to the pad allows cold air in through that tiny space. Though I was warm I did wake up a few times to the breeze. Not a big deal, but for $400 I shouldn't have that. Quality bag none the less.

    Light as a feather.

    • Familiarity: I've used it once or twice and have initial impressions

    First of all, this bag weighs nothing, and stuffs down to nothing, which is a huge bonus if you're trying to save weight and space in your pack. The mummy shape feels way roomier than a lot of other mummies I've used in the past - I didn't feel constricted at all. I did use the integrated sleeping pad sleeve for the Q-Core that I have, and it worked like a charm. No sliding around in the middle of the night!

    I used this bag on a 25 degree night and definitely woke up a few times feeling a bit cold, but it's really important to mention that I run cold, and temperature ratings ARE NOT comfort ratings. That being said, I would continue to use it for 25+ temps.

    If you have any further questions about this product I am happy to help! You can call me directly at 801-619-7488, or email me at

    Warm and Toasty!

    • Familiarity: I've used it several times

    This bag is super soft and has a great hand to it. My favorite feature has to be the integrated pad sleeve on the bottom. I am not usually a big fan of mummy shaped bags but with the footshape toe box this bag didn't feel like a mummy at all. It kept me warm all night, and usually, my feet are the first area that get cold and with the way the footbox is designed it helped to keep my toes nice and toasty all night. I really loved how big the top was too, super easy to get in and out of and it felt almost like a blanket instead of a sleeping bag.

    I’m between 5’11” - 6’ and wondering if I can get away with the Regular (5’10”) and not have to step up to the Long (6’6”). I really don’t want to pack the extra weight if I don’t have to.


    Best Answer

    Hey there Ezskanken!

    I honestly don't think that the sizes of the bags will create that big of a difference if any at all! Typically Backpacking and sleeping bags usually have an extra 1-3 inches of length! If you really do want to go with the regular length you can try it! It could be perfect for you if that is what you are looking for but I don't think this much weight will affect you too much!

    Feel free to contact me directly via the information left on this review or hop on to our live chat for more information! I've included the weight and compressed stuff size of these bag sizes!

    Bag Weight:

    Reg: 2ld 2oz

    Long: 2lb 3oz

    Compressed Bag Size

    Reg: 7inx7.5

    Long: 7x77.5

    Fill Weight:

    Reg: 14oz / 450g

    Long: 16oz / 451g

    Unanswered Question

    Can this bag accommodate a 25" wide pad (2.5" thick) at all? Is says that it takes a 20", but I'm curious if it could be stretched to be used with the Thermarest XTherm Large.