Arc UL Configuration Page

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The advanced Ultralight Series of Arc UL quilts are available in a wide temperature range designed with the lightest materials.

Custom features including sizing and weight saving options. 

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Custom item. Multi week lead time.


From this page all temperature ratings, sizing options and accessories of the Arc UL are configured

The Arc UL quilt is a specialists' tool, with lowest weight and bulk as the guiding design parameters. Features, functions and materials are all dialed in to meet the UltraLight goal.

Fabrics and Hardware

The Arc UL is built with the lightest fabrics we have been able to source. When using materials as thin as the unique Membrane .66 and Quantum equivalents, some compromise in durability and longevity must be anticipated. Generally though, in the hands of experienced users, normal life spans can be achieved with proper care.

Besides the custom sourced shell and liner materials, we also consider shock cords, buckles, snaps and other notions as specific targets for UL optimization, further shaving grams. 

Temperature Ratings

The Arc UL is available from a 30°F summer style quilt all the way down to 5°, in steps geared to fit the most useful seasonal applications. By far the most popular all-round rating is the do-it-all 20°.


A six step measure of the inside useful length in 5" increments is used parallel to the subjective and sometimes confusing Small to X-Long moniker. Using this system you can choose how far up the quilt reaches when lying on your back. Reaching just the chin level is the absolute shortest anyone should go, and then only on quilts for the warmer seasons. Forehead is the best compromise of low weight - efficient coverage.  As always, it is prudent to size up if in doubt. If just a little too short one tends to compress the foot area insulation to the detriment of cold feet.

Furthermore the shoulder and foot area widths can be customized for individual needs and sizing. Typically a 2 season quilt can be built a little narrower than a winter oriented set-up. If you're new to backcountry quilts, experiment at home with a blanket before committing to a sizing setup. 

Foot End Design

The Arc UL quilts are offered in two foot box configurations, also in the menu below. The traditional Arc design is a 24"-28" permanently closed section finished with a round bottom piece sewn in place. In other words, a sight familiar from high-end mummy bags.

The Vector foot end is a modular concept that allow the user to switch from closed to blanket style open foot area in a few simple steps. This option, while very adaptable to changing conditions, lack a little in thermal efficiency compared to the regular Arc. It also adds a small amount of weight, for those who count every gram. A page with a few pics detailing the foot box options is here.

What's in the box?

The quilt, a set of quilt straps, a silnylon stuffsack and a large breathable storage sack.

Go to the bottom of this page for the full Arc UL Configuration Menu!

Temperature Ratings Available30° - 20° - 15° - 5°
Length and width choices affect fill weight by roughly ½ to 1 ½ oz, depending on temperature rating.

After saving your customized product, remember to add it to your cart.



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32 deg Quilt

After a long day on the trail I see myself dreaming of climbing into my quilt with its ultralight (15.8oz), ultrasoft feel, snugging around my shoulders. I have been cosy and warm in all conditions down to -1C so far and it is my number one sleeping option. Thank you Jan for your advice in helping me choose the right one for me.


    This Quilt will set you FREE

    I purchased my Arc UL quilt about a year ago and have nothing but high praise for it. I've used the bag for 55 days of hiking in Alaska, 40 days in the Grand Canyon, and a week of hithhiking/trainhopping in between. The quilt has been soaked, dragged, stuffed and generally abused constantly, and does not show a single sign of wear. It is insanely warm (20 degree), unbelievably warm, and ridiculously compact. Nunatak could charge twice as much for these wonders and it would be worth every penny. Do yourself a favor, buy one and never worry about a cold night again. Thank you for the worlds lightest mobile home Nunatak!


      Quilt & Jacket

      Review from 05/05/2016:

      Jan, The quilt and jacket arrived safely at my door step. Never have I received so large a box weighing so little, and with such wonderful things inside. They are absolutely perfect. Thank you so much for your excellent work. I really appreciate it. -Niles

      • 0 out of 1 people found this review useful.


      Review from 07/26/2016:

      Loved that Arc quilt in Colorado !! Getting the Nano quilt for the JMT - you guys are great . Thanks !!

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        Arc UL Configuration Page

        Arc UL Configuration Page

        The advanced Ultralight Series of Arc UL quilts are available in a wide temperature range designed with the lightest materials.

        Custom features including sizing and weight saving options. 

        Product Options
        Temperature Rating
        The all time most popular choice is the versatile 20°F.
        30° is considered a 2 season rating, while 5° qualifies for light 4 season use.
        Inside Length
        The useable length measured from inside the footbox to the top hem, without compromising the insulation loft. For example, if you're 6' tall and want the quilt to reach over your head, choose 73".
        Shoulder Width
        54" is a good standard for regular sized folks who doesn't toss around too much. For winter bags go one size up.
        Foot End Style
        The Arc is the well known enclosed footbox sewn with a rounded bottom piece.
        The Vector gives you the option of opening up the quilt's foot area to a blanket style appearance. This comes with a slight compromise in thermal efficiency and about an ounce weight (30g) increase.
        ARC. Permanently Enclosed Foot Box
        VECTOR. Convertible - Blanket to Enclosed
        Footbox Size, Arc & Vector Models
        38" is the male size 10 shoe standard. Adjust accordingly.
        Shell Fabric

        Please go to the Fabric Page for help choosing the shell material.

        Liner Fabric
        Down Type
        Choosing Hyper-Dry moisture resistant down will help combat the effects of perspiration, misting tents and damp air. Nunatak products made with Hyper-Dry down will have a slight increase in bulk over those made with regular down. In some instances they may contain an additional 5% of fill weight.
        Down Overfill
        Cold sleeper? Consider adding a few ounces of extra fluff.
        Strap package
        Straps snugs the quilt around you and/or the sleeping pad. Options are: None (really?), ultralight shock cord style controllers, or the fully featured standard ¾" strap package.
        Gamut Climashield Over-quilt Compatability
        This mod makes a future over-quilt application as effective as possible. It adds snap buttons in the places needed, plus stores a record of your product's finished measurements and attachment points.