Arc UL 30°F - 25°F

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Due to move this product is unavailable until late 2022.

The Arc UL quilts are designed for optimal efficiency in the environments met by long distance hikers.Custom features including sizing and weight saving options. 

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Due to move this product is unavailable until late 2022.

A few things to keep in mind:

  1. We measure the actual width from the finished quilt's inside, without stretching. 
  2. The differential cut makes the inside narrower/shorter than the outside.
  3. Our sizes are real life, so will get you a quilt generally wider/longer than other brands with similar specs.
  4. The measured length does not include the draft collar.

Appropriate use

These two quilts are designed to balance the lowest possible weight and bulk with the level of comfort needed in the western US mountains during the summer hiking season. 

The 30° Arc UL is warm enough to serve as a general purpose quilt for an experienced backpacker.

The 25°F is the sweet spot for folks not knowing if a changing climate really warrants a 20°F quilt anymore.

20°F and 15°F quilts are available here

Fill and Loft

The 900 fp down loft is a between 1.90” and 2.25”.  Fill volumes for either level are detailed in the charts.


The length is in 4" increments. The chart numbers interprets where the quilt top is when on your back. In open mode reaching just the chin level is the absolute shortest anyone should go, and then only on quilts for the warmer seasons. Reaching the user's forehead is the best compromise of low weight - efficient coverage. As always size up if in doubt. Bags and quilts cut too short tends to compress the foot area insulation to the detriment of cold toes.

Adequate width in the shoulder to hip region is crucial for sleep comfort and draft control. A ball park figure to achieve optimal performance is your shoulder circumference plus 6"-10". The Arc UL does not taper inwards until below hip level.

Newcomers to backcountry quilts can also experiment with a blanket before committing to a width. 

Foot End Design

The traditional Arc design is a permanently closed section finished with a round bottom piece sewn in place. A design common with high-end mummy bags.

Shell Material Choices

More details on the Fabric Page, found in the top menu under Materials.

Ultralight: 10d ultralight breathable shell. 

This ultralight fabric creates a comfortable sleep environment at the lowest weight. While providing very little protection from moisture, the superior breathability allows it to dry quickly in the sun. Ideal for users seeking the lowest weight.

Classic: 15d lightweight breathable shell.

Same non-existent moisture protection as the 10d above, but a significant increase in durability and tear strength. Expect a weight gain up to one ounce, depending on size.

Moisture protection for select areas: 7d ultralight waterproof/breathable shell.  

With 7d wp/b covering the outer foot section and top draft collar you can protect the down where it typically wets out the most, while leaving the large mid section fully breathable. For use in the modern single wall tent where rampant condensation often collides with the lower end of sleeping bags. Also, the draft collar is protected from moist exhalations. A very versatile setup.

The 7d wp/b is coated fabric, yet has a very light denier count, and as such adds under 5% to the total weight over the 10d option.

Liner Material Choices

Long term wear on quilt fabrics is most pronounced on the inside liner material. To anticipate this the Arc UL can be upgraded to our soft, durable 20d Taffeta black liner, specifically developed for sleeping bags. Expect one ounce of weight gain.


This optional synthetic Apex insulated bag is a booster option for extending the use of your quilt well into the colder season, while providing superior moisture management. 

Depending on the user the overbag can add 15°F or more to the rating of your base quilt, while completely eliminating drafts. The latter is probably the most crucial element for a winter specific quilt based sleep system; and very hard to maintain with a quilt/quilt setup.

The dampness inevitably forming on the outer surface will mostly affect the quick drying synthetic while the down mass stays drier. This applies to body moisture pushed outward; and dew, frost and shelter induced condensation from the environment. For longer trips in inclement conditions this becomes a crucial aspect of staying warm. 

This overbag is zipper-less with a closed mummy style foot box, and features a custom cut to match your quilt sizing specs and curvature thus avoiding excessive compression of the lofted down. A draw cord at the top seals in the warmth. It uses 2.5 oz weight Apex. 

The fabric used is a highly breathable 10d nylon, with smooth taffeta inside and ripstop out. All black. Average weight is 15oz, with small variances depending on the base quilt.

Additional applications includes emergency and summer stand alone use.

The overbag is also available for purchase at a later day here

What's in the box?

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

We also have additional articles with helpful pointers on selection and design:

Choosing the right Quilt

Designing with Down

Why Overfill?

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

Forest 10d shell with upgraded grey waterproof/breathable 7d foot and collar.

Purple 10d shell with upgraded grey waterproof/breathable 7d foot and collar.

Grey 10d shell with upgraded grey waterproof/breathable 7d foot and collar.

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



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Custom 2 season Quilt

Just opened the box. Impressive! The loft is fantastic, the construction top-shelf, the weight lovely, and the straps the perfect combination for my needs. I think by putting our heads together we designed exactly what I was dreaming. Can't wait to try this thing out.

  • 1 out of 1 people found this review useful.

Backyard test!

I cowboy camped in my yard in Nashua NH last night (December 2018). When I woke up it was 12°F with a very slight breeze. My nose was cold.

I had the Arc UL 30°F quilt and the Nano 40°F blanket (which ended up over only my legs by the time I woke up), and wore the balaclava. I was wearing a light wool base layer.

I was perfectly warm all night. The only cold was when I would move a little opening would form and a draft would blow extremely cold air for a second. The quilt and balaclava are amazingly warm. Glad I didn't get the 20°F quilt or I would have been too hot. And thanks for the matching custom purple fabric on everything.

  • 1 out of 1 people found this review useful.

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Arc UL 30°F - 25°F

Arc UL 30°F - 25°F

Due to move this product is unavailable until late 2022.

The Arc UL quilts are designed for optimal efficiency in the environments met by long distance hikers.Custom features including sizing and weight saving options. 

Product Options
Temperature Rating

The rating reflects the lowest temperature during which a well conditioned hiker can expect to remain comfortable throughout a full night. Adequate shelter and ground pad must be used.

30°F / 0°C. Includes differential cut
25°F / -4°C. Includes differential cut
Inside Length

To determine the correct length please refer to the measurements in the chart.

In betweener? Use this link

Shoulder Width

Measure around your widest part, including arms. Add 8-12” to this number for the best performance.

Wanting more options? Go here

50" Our narrowest size for slim folks who doesn’t toss and turn much; and experienced quilt users wishing to save weight.
56" The most popular size that fits most frames.
62" For bigger people and/or those who toss and turn.
68" Very wide quilt - sprawling coverage!
Footbox Size Circumference
40" is the male size 10-11 shoe standard. For side sleepers the 40" is good to size 12-13
Shell Material

Two options: Ultralight 10d for the lightest, most breathable and best lofting performance. 15d for more durability and tear resistance with only a small weight penalty.

Waterproof/Breathable Shell Options

This selection substitutes a 7d waterproof/breathable shell fabric to the lower third, plus the head opening. The large torso middle section remain with the classic 10d/15d breathable fabric.

No Thanks!
Grey Robic Weatherproof 7d - Applied Only to Lower Third and Top Draft Collar
Liner Material Options
Choose between lightest - the 10d - or long lasting comfort at the penalty of several ounces extra weight: the 20d
Black 10d taffeta - Lightest, most breathable
Black 20d taffeta - Durable, soft and comfortable but about an ounce heavier!
10d black taffeta in torso section, more durable 20d taffeta in foot section
Down Type

We use 900 fill power goose down, certified responsibly sourced.

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 untreated down.

Edge Tension Control

This design involves two user adjustable shock cords running lengthwise along the left and right quilt edges. On cold nights tension the cords to shorten the edges and draw them under you; during milder conditions completely slacken the cords to have the blanket throw feel.

Strap package

Straps snug the quilt around you and/or the sleeping pad.

Yes, include pad attach and under-body straps
Down Overfill
Adding overfill can prolong the life of the down, help maintain loft during moist conditions, boost the temperature rating by a small amount and keep the down volume from shifting. The amount depends on the product, the size and the rating.
No Thanks
Overfill in foot section
Overfill in torso section
Overfill evenly throughout
Optional Custom Sized Apex Overbag

50°F synthetic filled Apex over-bag providing a rating boost of 15°F.  It is custom cut to fit over the Arc UL without compressing the down insulation. Average weight is 18 ounces. Black 10d inside and out with a top draw cord.

No Thanks!
Yes, include a custom 50°F Apex over-bag
Stuff Sack
Our stuff sacks are pretty dope, but current weight saving trends in ultralight circles eschews this once crucial item. So, opt out and save $ while also being very current.
No stuff sack
Yes, please include a stuff sack
Your Measurements
Optional: Fill in the blanks to ensure getting the best fit. No changes will be made to your size selections without approval
Shoe Size