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Ultra-Sil Stuff Sack

Ultralight and slippery pack organization for the savvy packer and traveler

$12.95 – $22.95

Sleeping Bag Temperature Ratings Explained

The EN Rating scale is a scientific test to determine the warmth of a sleeping bag. The test produces a Lower rating (for male sleepers) and a Comfort rating (for female sleepers). Both are listed in the features table on the product page.

A unisex sleeping bag with a Lower limit of 14ºF means a man should be comfortable down to air temperatures of 14ºF. The same bag will also have a Comfort limit, in the realm of 27°F, so a woman would be comfortable down to an air temperature of 27ºF. These ratings require a sleeping mat with an R-Value appropriate for expected ground temperatures – without this, the sleeping bag itself is unlikely to keep the sleeper warm enough.

A variety of factors impact sleeping bag warmth - the above temperatures are merely guidelines, not guarantees. It’s important to think of a sleeping bag, an appropriately insulating sleeping pad and a liner as a sleep system. For example - if you plan on sleeping in nighttime air temperatures of 27ºF / -3°C, choose a bag with a gender-appropriate rating of 23°F / -5°C, plus a sleeping mat with an R-Value of 2.5 to 3, and consider a Reactor thermal liner.



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The Ultra-Sil Stuff Sack is an ultralight but durable solution using a 30D siliconized CORDURA® fabric. Ideal for organizing gear in your pack or bag, these stuff sacks incorporate a reinforced pull handle on the base, a durable pull tab at the top and are available in several great colors. 



Your scale will hardly notice the difference when you start using these

Best Use

Internal pack organization, packing up whatever you feel like belongs in a bag

What this bag could hold

2.5 liter: a phone (in a waterproof case), snacks, wallet & keys
4 liter: some snacks and drinks or extra layers

6.5 liter: a layer and a meal or so worth of food
9 liter: a puffy jacket & a sleeping bag or food for 2-3 days
15 liter: all your clothes for a trip
20 liter: a tent or any Sea to Summit sleeping bag
30 liter: paddle gear, overnight camp equipment or bike gear


  • Made of 30D Diamond RipStop Siliconized CORDURA®
  • The fabric is impregnated with silicone to make it waterproof to a hydrostatic head of 2000mm
  • The fabric has a slippery finish for easy packing
  • Reinforced pull handle on the bottom
  • Uses the smallest possible cord and cord lock for top closure
  • Bar tack reinforced in all stress points
  • All seams are double stitched for extra strength
  • Note: seams are not tape-sealed; therefore this product is not waterproof - only water resistant

Technical Features

Name missing article: technical-features/30d-ultra-sil


Cordura® is a special type of nylon yarn used for its strength. These yarns are used in two different product areas:

>  In the siliconized Ultra-Sil™ fabrics used in Ultra-Sil™ Dry Sacks, Stuff Sacks, Compression Sacks, Pack Covers, Travelling Light and Travel Essentials products
>  In the foot section of the extremely tough eVent® Quagmire Gaiters.

    Tech Specs

    XXS 2.5 LITER
    XS 4 LITER
    S 6.5 LITER
    M 9 LITER
    L 15 LITER
    XL 20 LITER
    XXL 30 LITER
    4 x 10 in / 11 x 22 cm
    0.5 oz / 13g
    5 x 12 in / 14 x 27 cm
    0.5 oz / 13g
    6.5 x 13 in / 17 x 30 cm
    0.6 oz / 17g
    7 x 15 in / 18 x 34 cm
    0.7 oz / 21g
    8.5 x 17 in / 21 x 40 cm
    1.0 oz / 28g
    9.5 x 19 in / 24 x 45 cm
    1.2 oz / 34g
    10.5 x 23 in / 26 x 55 cm
    1.4 oz / 40g


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