Arc UL 25°F, Medium - Reg Width

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The Arc UL quilts are designed for optimal efficiency in the environments met by long distance hikers.

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Sizing notes

  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

This quilt is comfort rated and designed to balance the lowest possible weight and bulk with the level of warmth needed in the western US mountains during the summer hiking season. 

Fill and Loft

The 900 fp down loft is 2.25" for the 25°F rating


The length number reflects where the quilt top edge lands 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.

Differential Cut

All our quilts and bags with down fill are sewn with the outside shell oversized in length and width compared to the liner, aka Differential Cut. This allows the down fill to achieve maximum loft, which in turn makes the product warmer. Differential cut also helps holding the down in place so developing cold spots are minimized. 

Proper Down Fill Amounts and Optimized Baffle Shape

These are two crucial design aspects also relating to maximum loft and down retention. This ensures the cold weather performance is equal to the given comfort rating. 

Draft Collar

The Arc UL is built with an overfilled 4" wide draft collar with cinch cord. The adjustment toggle off to the side of center so it does not dangle in one's face.


The adjustable Edge Tension Control eliminates the need for quilt straps in all but the coldest, most challenging conditions. ETC

Quilt Straps

Two elastic straps cinches the quilt edges together under the user. One of these also helps center the user on the pad. Removable for a tangle free experience when conditions allow. Straps

Shell/Liner Material 

10d ultralight Ripstop Nylon breathable shell. 

Combination liner: 10d Taffeta torso/20d Taffeta foot section for added durability

These ultralight fabrics 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. 

What's in the box?

The US made quilt (from imported materials), a set of quilt straps, an optional silnylon stuffsack and a large breathable storage sack.

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




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Arc UL 25°F, Medium - Reg Width

Arc UL 25°F, Medium - Reg Width

The Arc UL quilts are designed for optimal efficiency in the environments met by long distance hikers.

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.

25°F / -4°C. Includes differential cut
Inside Length
70" - Medium
Shoulder Width
56" The most popular size that fits most frames.
Footbox Size Circumference
Shell Fabric

Grey Ripstop 10d - Lightest, most breathable
Liner Material Options
10d black taffeta in torso section, more durable 20d taffeta in foot section
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.

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. For most quilts/bags the overfill amount ranges from 45-65 grams of extra down

No Thanks
Overfill in foot section
Overfill in torso section
Overfill evenly throughout
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
2 Side Mounted Underbody/Pad Straps - Removable.
Stuff Sack
Yes, please include a stuff sack
No stuff sack