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Ultra-Sil Nano Dry Sack

Backpack organization for gram counters

4.7 star rating 12 Reviews

$14.95 – $34.95

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 23ºF means a man should be comfortable down to air temperatures of 23ºF. The same bag will also have a Comfort limit, in the realm of 32°F, so a woman would be comfortable down to an air temperature of 32ºF. 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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Designed with ultralight backpacking in mind the Ultra-Sil™ Nano™ Dry Sack is made from lightweight  15D siliconized Nylon. With the use of featherweight 15D fabric, these are perfect for use inside your pack to keep gear organized and dry. Using a hypalon roll-top closure that doesn't wick moisture, an oval base for easy packing, these are fully seam sealed for water resistance. Ideal for backpacking, climbing, cycle touring and modular packing where lightweight and low bulk is key. 

Read more about which dry bag is right for you HERE



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


Should be kept in another dry bag or backpack

Best Use

Backpacking, Travel, Bike Packing

What this bag could hold

1 liter: wallet, ear buds / personal headphones
2 liter: first aid essentials (avoid hard or sharp objects), gloves/beanie hats

4 liter: shell jacket, gloves/beanie hat, or day-hiking essentials
8 liter: a two-season down sleeping bag or quilt, or dry clothes for backpacking
13 liter: a three-season down sleeping bag, or all your clothes for an ultralight backpacking trip
20 liter: a three-season synthetic sleeping bag plus a Reactor Liner
35 liter: use as a full pack liner for overnight (30+ Liter) ultralight backpacks


  • Ultra-Sil Nano 15D Nylon fabric for high strength to weight performance
  • Ultra-Sil Nano has a 1,200mm hydrostatic head
  • Waterproof hypalon roll-top closure does not wick moisture
  • Waterproof seams - double stitched and tape sealed
  • Reinforced stitching on all stress points
  • Siliconized fabric with a smooth finish for easy packing
  • Compact and super lightweight with an oval base design for easy packing
  • This product is not intended for boating or marine use
  • Intended for use inside a bag or backpack

Technical Features

15D Ultra-Sil®

One of the lightest coated fabrics that Sea to Summit manufactures, the 15 Denier Ultra-Sil is a siliconized nylon fabric with a polyurethane (PU) inner coating for mild waterproofing. This ultralight fabric has a 1,200mm hydrostatic head.

Tech Specs

Product Details

Best Use
Backpacking, Hiking, Bike Packing & Travel
Waterproof roll-top closure
Ultralight Ultra-Sil Nano 15D nylon fabric
Oval base to resist rolling and an ideal height-to-width ratio for easy packing
5.1 x 3 x 9.4 in / 13 x 7.5 x 24 cm
0.5 oz / 13g
5.9 x 3.7 x 11.2 in / 15 x 9.5 x 28.5 cm
0.6 oz / 16g
6.7 x 4.4 x 13 in / 17 x 11.2 x 33 cm
0.7 oz / 19g
7.9 x 5.9 x 18.5 in / 20 x 15 x 47 cm
0.8 oz / 24g
8.9 x 6.5 x 20.5 in / 22.5 x 16.5 x 52 cm
1.0 oz / 28 g
10.2 x 7.9 x 24.8 in / 26 x 20 x 63 cm
1.3 oz / 36g
12.2 x 9.8 x 27.6 in / 31 x 25 x 70 cm
1.6 oz / 46g
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