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Ultra-Sil Pack Liner

Keep your pack organized and dry without a bulky rain cover

$34.95 – $44.95

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.



The Ultra-Sil™ Pack Liner won the prestigious Backpacker Editors' Choice award in 2006 and this award winner is an excellent solution for keeping contents of your pack dry. It's made of 30D Ultra-Sil™ CORDURA® brand fabric, making it super lightweight and is an oval shape to fit inside packs easier. The extra wide opening roll-top closure folds in three before being rolled and sealed with the low profile buckles. We've used bright colors to help with visibility when packing and unpacking, and a 50L, 70L and 90L size range to cover all options and bag sizes.



Keep it inside your pack and away from hard edges and corners.


Should be kept in another bag or backpack

Best Use

Backpacking, Travel

Size Guide

50 liter: will fit in a 50-liter pack or smaller
70 liter: will fit in a 70-liter pack or smaller

90 liter: will fit in a 90-liter pack or smaller


  • Ultra-Sil Pack Liner opens wide for easy packing when it's inside a pack
  • Unique top closure: extra fabric at the top folds in and hook and loops into place, then rolls down, creating a more compact closed loop at the top
  • Made of PU coated siliconized CORDURA®
  • Waterproof hypalon roll-top closure does not wick moisture
  • Waterproof seams - double stitched and tape sealed
  • Low profile buckles
  • Slippery finish for easy packing

Technical Features

30D Ultra-Sil®

An incredibly lightweight yet durable fabric used in a large number of Sea to Summit products. This 30 denier Nylon is made with CORDURA® yarns for strength, woven into a ripstop pattern. Two versions of the fabric are used:

  • water-resistant products (such as the Ultra-Sil™ Stuff Sacks) are siliconized on both sides for ultimate packability
  • waterproof products (such as the UltraSil™ Dry Sack are) siliconized on the outside and PU-coated on the inside to allow seam taping.

Both versions have a hydrostatic head greater than 2000mm – which makes them more than adequately waterproof for the types of environments they are intended for.


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

    Product Details

    Best Use
    Backpacking, Hiking & Bike Packing
    Waterproof durable roll-top closure with Velcro
    Lightweight Ultra-Sil nylon body
    Tapered with oval base for easy packing / stowing in your backpack
    50 LITER
    70 LITER
    90 LITER
    19 x 6 x 31 in / 48 x 15 x 79 cm
    50 L / up to 3000 cu in
    3.4 oz / 95 g
    20 x 8 x 35 in / 50 x 20 x 89 cm
    70 L / up to 4300 cu in
    3.9 oz / 110 g
    22 x 10 x 48 in / 56 x 25 x 122 cm
    90 L / up to 5500 cu in
    5.5 oz / 155 g


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