Feathered Friends Swallow UL 20 Review – Lightweight Package

Feathered Friends Swallow UL 20 Review: Discover why this top-tier sleeping bag is a favorite among backpackers for its warmth, lightweight design, and durability.
Feathered Friends Swallow UL 20

Feathered Friends Swallow UL 20

Explore the Ultimate Balance of Warmth, Comfort, and Durability in the Feathered Friends Swallow UL 20
The Feathered Friends Swallow UL 20 is an exceptional sleeping bag offering superior warmth, lightweight design, and durability, ideal for serious backpackers.


Warmth & Insulation
Packability & Weight
Comfort & Fit
Durability & Materials
Versatility & Features


  • Exceptional warmth-to-weight ratio
  • High-quality materials
  • Comfortable fit
  • Versatile temperature regulation
  • Durable construction
  • Water-resistant down


  • Premium price
  • Limited width
  • Limited color options
  • Availability issues


Brief Overview

The Feathered Friends Swallow UL 20 is a high-performance sleeping bag designed for avid backpackers and campers who prioritize lightweight gear without compromising warmth and comfort. This sleeping bag, part of the esteemed Feathered Friends lineup, is engineered to deliver exceptional thermal efficiency and packability, making it an ideal companion for multi-day treks and alpine adventures.

Initial Impressions and Context of Testing

Upon unboxing the Feathered Friends Swallow UL 20, the first thing that struck me was its impressive balance of weight and loft. Weighing in at just over a pound, the Swallow UL 20 promises warmth down to 20°F, thanks to its premium 900+ fill power goose down insulation. The sleeping bag’s exterior is crafted from Pertex Endurance fabric, known for its durability and water resistance, giving it a sturdy yet sleek feel.

I tested this sleeping bag on a week-long backpacking trip in the Rockies, where the temperatures dipped well below freezing at night. This provided an excellent opportunity to evaluate the Swallow UL 20’s thermal performance and overall usability in challenging conditions. The bag was tested both in a tent and under a tarp to gauge its versatility and reliability across different shelter setups.

These initial tests aimed to push the sleeping bag to its limits, ensuring that any strengths and weaknesses would be readily apparent and providing a thorough understanding of how the Swallow UL 20 performs in real-world scenarios.

Technical Specifications

Key Features and Technology

The Feathered Friends Swallow UL 20 is designed with cutting-edge technology to ensure maximum performance in a lightweight package. Here are the standout features:

  • 900+ Fill Power Goose Down: Utilizes some of the highest quality down available, providing exceptional warmth-to-weight ratio.
  • DownTek Water-Resistant Down: Treated to resist moisture, ensuring the down maintains loft and warmth even in damp conditions.
  • Pertex Endurance Fabric: The outer shell is made from this highly durable and water-resistant fabric, providing excellent protection against the elements.
  • Full-Length YKK Zipper: A smooth, reliable zipper that extends the length of the sleeping bag for easy entry and exit, with a draft tube to prevent heat loss.

Design and Materials

The Feathered Friends Swallow UL 20 is meticulously designed with both form and function in mind. Here’s a closer look at its construction:

  • Outer Shell: Crafted from Pertex Endurance fabric, known for its lightweight, yet robust nature. It provides a barrier against wind and moisture without sacrificing breathability.
  • Lining: Made from a soft, down-proof fabric that feels comfortable against the skin while preventing down leakage.
  • Baffle Construction: Continuous horizontal baffles ensure an even distribution of down, preventing cold spots and maximizing thermal efficiency.

Dimensions and Weight

  • Weight: Approximately 1.6 pounds (710 grams), making it one of the lightest 20°F sleeping bags on the market.
  • Length Options: Available in multiple lengths to accommodate users of different heights—standard (up to 6’0″), long (up to 6’6″).
  • Width: A tapered mummy shape offers a snug fit that enhances thermal efficiency while still providing enough room for comfortable movement.

Temperature Rating and Insulation

  • Comfort Rating: Rated to 20°F (-6°C), making it suitable for three-season use in a variety of conditions.
  • Insulation: High-quality 900+ fill power goose down provides unmatched warmth while keeping the sleeping bag lightweight and compressible.

Additional Features

  • Adjustable Hood: The hood can be cinched tightly around the head to prevent heat loss and ensure maximum warmth.
  • Draft Collar and Tube: Both features work together to seal in warmth and keep out cold drafts, enhancing overall comfort.
  • Compression Sack and Storage Bag: Included for easy packing and long-term storage, ensuring the sleeping bag retains its loft and performance.

These technical specifications highlight the Feathered Friends Swallow UL 20’s commitment to quality, performance, and thoughtful design, making it a top choice for serious backpackers and outdoor enthusiasts.

Performance Evaluation

Fabric Performance

  • Breathability: The Feathered Friends Swallow UL 20 features a Pertex Endurance shell, which excels in breathability. This material effectively wicks moisture away from the body, preventing clamminess and ensuring a comfortable night’s sleep even in humid conditions. During my testing in the Rockies, I found that the fabric maintained excellent airflow, which is crucial for managing body temperature throughout the night.
  • Waterproofing: The DownTek water-resistant down treatment and Pertex Endurance fabric work together to provide reliable waterproofing. This combination effectively repels moisture, ensuring the down stays dry and retains its insulating properties. During a night of unexpected rain, the outer shell kept the sleeping bag dry without any noticeable dampness inside.
  • Durability: The Pertex Endurance fabric is not only lightweight but also highly durable. It withstood the rigors of backcountry use, including rough ground and occasional abrasions from gear. The stitching and construction showed no signs of wear after a week of intensive use.

Weather Resistance

  • Cold Weather Performance: Rated for 20°F, the Swallow UL 20 performed admirably in sub-freezing temperatures. On nights where temperatures dropped to the low 20s, the sleeping bag provided consistent warmth. The draft collar and tube, combined with the adjustable hood, effectively sealed in heat, preventing cold air from entering.
  • Wind Resistance: The Pertex Endurance fabric offers excellent wind resistance, which is crucial in exposed, high-altitude environments. Even during windy nights, the sleeping bag maintained its thermal efficiency, providing a cozy and secure sleeping environment.
  • Moisture Management: The DownTek treatment ensures that the down insulation resists moisture, maintaining loft and warmth. This feature was particularly useful in damp conditions, where the sleeping bag remained dry and comfortable, enhancing the overall sleep experience.

Practical Features

  • Zippers: The full-length YKK zipper is a standout feature, providing smooth operation without snagging. The draft tube along the zipper prevents heat loss, ensuring consistent warmth throughout the night. The zipper’s two-way functionality allows for easy ventilation, which is beneficial in warmer conditions.
  • Draft Collar and Tube: These features are essential for retaining warmth. The draft collar comfortably seals around the neck, while the draft tube runs along the zipper, blocking out cold drafts. Together, they significantly enhance the sleeping bag’s thermal efficiency.
  • Hood Adjustments: The adjustable hood is designed to cinch tightly around the head, minimizing heat loss. The design allows for easy adjustments, ensuring a snug fit without causing discomfort.
  • Compression Sack and Storage Bag: The included compression sack makes packing the sleeping bag a breeze, reducing its size to fit easily in a backpack. The storage bag provided is ideal for maintaining the loft and longevity of the down during off-season storage.

In summary, the Feathered Friends Swallow UL 20 excels in fabric performance, weather resistance, and practical features, making it a reliable choice for serious backpackers and outdoor enthusiasts seeking a lightweight yet warm sleeping solution.

Fit and Comfort

Sizing and Fit

The Feathered Friends Swallow UL 20 is designed with a tapered mummy shape, optimizing thermal efficiency while still allowing for a comfortable fit. Available in multiple lengths, including standard (up to 6’0″) and long (up to 6’6″), this sleeping bag caters to a variety of body types and heights. During testing, I found that the standard size provided ample room for my 5’10” frame, with enough space to comfortably move my legs and feet.

The shoulder and hip girth are well-balanced, offering a snug fit that enhances warmth without feeling restrictive. This careful design ensures that the sleeping bag can effectively trap body heat while allowing for sufficient freedom of movement. The footbox is particularly noteworthy, providing extra space to avoid compressing the down and ensuring that your feet remain warm and comfortable throughout the night.

Comfort During Various Activities

The Swallow UL 20 excels in providing comfort across a range of outdoor activities, from high-altitude mountaineering to casual camping. Here are some of the comfort features that stood out during my testing:

  • Sleeping Position Adaptability: The design accommodates various sleeping positions, whether you’re a back, side, or stomach sleeper. I found that the bag’s shape allowed me to shift positions without feeling constricted, which is crucial for a good night’s sleep in the backcountry.
  • Soft Interior Lining: The interior lining is made from a soft, down-proof fabric that feels gentle against the skin. This added touch of comfort makes a significant difference, especially on long trips where every bit of comfort counts.
  • Temperature Regulation: The breathable Pertex Endurance fabric and DownTek-treated down work together to regulate temperature effectively. On warmer nights, the two-way zipper allowed for easy ventilation, while on colder nights, the adjustable hood and draft collar helped retain heat.
  • Minimal Bulk: Despite its impressive thermal performance, the Swallow UL 20 remains lightweight and compact. The low bulk makes it easy to pack and carry, reducing the overall load on long hikes.

Real-World Comfort Experience

During my week-long backpacking trip in the Rockies, I had the opportunity to fully experience the Swallow UL 20’s comfort features. One particularly chilly night, with temperatures dipping to the low 20s, I was able to cinch the hood tightly around my head, and the draft collar effectively sealed in warmth, preventing any cold air from seeping in. Despite the cold, I slept soundly, thanks to the thoughtful design and high-quality materials.

On another night, when temperatures were milder, I partially unzipped the bag to allow for better airflow. The two-way zipper made this adjustment easy without compromising the overall fit and comfort of the sleeping bag. This adaptability to different weather conditions and sleeping positions is a testament to the Swallow UL 20’s versatile design.

In conclusion, the Feathered Friends Swallow UL 20 offers an exceptional fit and comfort level, making it a top choice for outdoor enthusiasts who demand both performance and a restful night’s sleep in the wilderness.

Pros and Cons


  • Exceptional Warmth-to-Weight Ratio: The 900+ fill power goose down provides excellent insulation while keeping the sleeping bag lightweight and compressible. This makes it ideal for backpackers who need to minimize weight without sacrificing warmth.
  • High-Quality Materials: The Pertex Endurance shell is both durable and water-resistant, ensuring the sleeping bag can withstand harsh conditions and keep you dry.
  • Comfort and Fit: The tapered mummy design offers a snug fit that enhances thermal efficiency while providing enough room for comfortable movement. The soft interior lining adds a touch of luxury, making long nights in the backcountry more bearable.
  • Versatile Temperature Regulation: The two-way YKK zipper allows for easy ventilation on warmer nights, while the adjustable hood and draft collar help retain heat in colder conditions. This adaptability makes the Swallow UL 20 suitable for a wide range of temperatures.
  • Durable Construction: The robust stitching and high-quality materials ensure longevity, making this sleeping bag a reliable investment for serious outdoor enthusiasts.
  • Water-Resistant Down: The DownTek-treated down resists moisture, maintaining loft and insulating properties even in damp conditions. This feature is crucial for maintaining warmth in unpredictable weather.


  • Premium Price: The high-quality materials and advanced design come at a premium cost, which may be prohibitive for budget-conscious buyers. However, for those who prioritize performance and durability, the investment can be justified.
  • Limited Width: While the tapered mummy design enhances thermal efficiency, it might feel too restrictive for those who prefer a more spacious sleeping bag. Side sleepers or individuals who move around a lot during the night might find the fit somewhat confining.
  • Color Options: The Swallow UL 20 has limited color options, which might not appeal to those who prefer a wider variety of aesthetic choices in their gear.
  • Availability: Due to its high demand and specialized nature, the Swallow UL 20 may sometimes be out of stock, leading to potential delays in acquiring this sleeping bag.

In summary, the Feathered Friends Swallow UL 20 excels in warmth, comfort, and durability, making it a top-tier choice for serious backpackers and outdoor adventurers. However, its premium price and tapered fit may not suit everyone’s preferences or budget.

Comparative Analysis

When comparing the Feathered Friends Swallow UL 20 to the Kelty Cosmic Down 20 and the Western Mountaineering UltraLite 20, several distinctions emerge, highlighting both strengths and potential limitations of each sleeping bag.

Feathered Friends Swallow UL 20 vs. Kelty Cosmic Down 20

The Feathered Friends Swallow UL 20 stands out for its premium 900+ fill power goose down and Pertex Endurance fabric, offering exceptional warmth-to-weight ratio and durability. In contrast, the Kelty Cosmic Down 20 utilizes 550 fill power down, which, while still effective, does not provide the same level of insulation or compressibility as the Swallow UL 20. The Swallow UL 20 is significantly lighter, weighing approximately 1.6 pounds compared to the Cosmic Down’s 2.5 pounds, making it a better choice for ultralight backpackers. However, the Kelty Cosmic Down 20 is much more budget-friendly, making it a good option for those who need a reliable, affordable sleeping bag for moderate conditions.

Feathered Friends Swallow UL 20 vs. Western Mountaineering UltraLite 20

The Western Mountaineering UltraLite 20 is another top-tier sleeping bag, similar to the Swallow UL 20 in its use of high-quality 850+ fill power goose down. Both bags are designed for serious backpackers, offering excellent warmth-to-weight ratios and high durability. The UltraLite 20 is slightly heavier, weighing in at about 1.75 pounds, but it provides a slightly roomier fit compared to the Swallow UL 20’s more tapered design. This can be a deciding factor for users who prefer a bit more space. Additionally, Western Mountaineering’s reputation for meticulous craftsmanship and long-lasting products is well-matched by Feathered Friends, making both sleeping bags excellent investments. However, the Swallow UL 20’s use of DownTek-treated down for added moisture resistance may offer a slight edge in wet conditions.

In conclusion, while the Feathered Friends Swallow UL 20 excels in lightweight performance and moisture resistance, the Kelty Cosmic Down 20 offers a more affordable, albeit heavier, option for moderate use. The Western Mountaineering UltraLite 20, comparable in quality and performance, provides a roomier alternative with similar high-end features.


The Feathered Friends Swallow UL 20 is a top-tier sleeping bag that excels in lightweight performance, warmth, and durability. Its 900+ fill power goose down and Pertex Endurance fabric make it an outstanding choice for serious backpackers and outdoor enthusiasts who demand high performance in a compact package. The water-resistant DownTek-treated down ensures reliable insulation even in damp conditions, and the thoughtful design features, such as the adjustable hood and draft collar, enhance comfort and warmth.

While the Swallow UL 20 comes at a premium price, its exceptional quality and performance justify the investment for those who prioritize weight savings and thermal efficiency on their adventures. Ideal for three-season use and versatile enough for a variety of conditions, this sleeping bag is best suited for dedicated hikers, mountaineers, and backpackers who need a dependable and lightweight sleeping solution.

Further reading