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Sea to Summit down sleeping bags, part 3: certification for down fill and content

This spring season, Sea to Summit has released a groundbreaking new line of down-filled sleeping bags. The Sea to Summit down sleeping bags are so packed with technology, it’s more than we can adequately describe on, so we’ll be examining one technological aspect each day all week. Curious how Sea to Summit’s designers have pushed the envelope with their new down sleeping bag designs? Read on. Today, we are looking at the unique certification provided with each sleeping bag!


This must be the least-exciting title in this article, but it also might be the boldest statement Sea to Summit is making with this line of down sleeping bags. Sleeping bag makers love to throw out big numbers for the fill-power of the down being used in a given bag: 800, 850, 850+ or even 900! While these numbers sure look great when they’re embroidered on the side of your sleeping bag, there’s typically no way to be sure that the down used for that particular bag actually achieves those lofty (pun intended) standards.

Well, Sea to Summit is meeting this one head-on. For all of the sleeping bags using the 850+ loft down, a certificate from the International Down Feather Laboratory (IDFL) is included inside the package. This certificate identifies the exact fill power of the goose down used. Sea to Summit guarantees each bag is filled with at least 850-fill down.

In other words: no smoke, no mirrors. When you buy a Sea to Summit down sleeping bag that says “850+ loft” on the side, there’s absolutely no question that bag is filled with down of at least that quality, because the batch of down used in that specific sleeping bag has been independently certified.

This certification also confirms the down content, an overlooked assessment of quality in addition to fill-power; the 850+ loft down used in these sleeping bags is 95% down plumules, which combine to form clusters and achieve the best loft. Mature goose down plumules cling together, providing the best insulation available and lasting a lifetime.

In fact, I took a look inside the envelope from one of the first bags that hit our warehouse (check out the photo at upper left), and it grades out with a loft of 905.

No other down sleeping bag manufacturer is willing to back up their claims to this extent. It’s easy to have a single batch of down tested to a given fill-power; it’s much harder to have every batch of down tested, by a third party, and it’s borderline ludicrous to sell those individual test results along with the bags. Yet this is what Sea to Summit is doing, and when you zip into a Sea to Summit down sleeping bag and count on it to keep you comfortable — or alive — throughout the night, you’ll experience the peace of mind that comes with knowing exactly what it is you’re zipping into!


On Monday we wrote about the 3D NanoShell, and yesterday we discussed the 3D Sidewall and Reverse differential cut. Check back throughout the week for articles about the EN temperature rating system and the features included in each of the four lines of sleeping bags.

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