The Arc'teryx Cerium SL is a super light and simple down jacket meant for use strictly as a midlayer insulation piece.
The super light Cerium SL works best as a midlayer, but can be worn as an outer layer when hanging around camp.
The Cerium SL was the lightest jacket we reviewed by a fair margin, which also means it has the least amount of down insulating you from the elements. While it is filled with high quality 850 fill down (which provides a very high level of warmth for the weight) it is not thick enough to be terribly warm. This model also lacks a hood, making it fit well as a midlayer but preventing it from being incredibly warm as an outer layer.
Additionally, the fabric and construction do not provide much protection from wind, so this is, as advertised, a layer limited to use as an insulating midlayer--best when covered by a more rugged hard- or softshell outer layer. In aerobic pursuits, however, the outer fabric revealed its lower breathability, and our reviewers would overheat sooner in this jacket than the other similar weight jacket and award winner, the Mountain Hardwear Ghost Whisperer - Women's.
This was the lightest jacket in our review, not even approached in weight except by the Mountain Hardwear Ghost Whisperer. The Cerium SL, however, is much more limited in use and function.
The Cerium SL is the lightest jacket we reviewed, but it does not include a hood. Overall we think the fit and construction is sleek and stylish.
Excellent down quality and stunningly lightweight outer material made this jacket by far the most compressible model we tested.
The Cerium SL has Arc'teryx's signature Down Composite Mapping. In places where the jacket is most likely to get compressed and/or saturated with water, they have stitched in Coreloft synthetic insulation instead of down. The idea is a great one, but in use it had a very counterproductive result. Our reviewers found that both Arc'teryx jackets we reviewed with this technology were the slowest to dry. Down breathes very well, and with a little body heat nearby it dries faster than the synthetic Coreloft. Our tests showed that the down bordering the Coreloft panels on the shoulders and cuffs stayed wetter longer because the synthetic insulation did not dry as fast, and dripped into the surrounding down panels. Additionally, water gathered in the cuffs and pooled inside the jacket looking (and feeling) much like a water balloon until squeezed out.
In more aerobic pursuits, we also found this jacket to breathe very poorly, especially when compared to the Ghost Whisperer.
The Arc'teryx Cerium SL, showing Down Composite Mapping feature on the cuff compartment with the Coreloft synthetic insulation. The synthetic insulation goes to about mid-forearm.
Style and Fit
The fit and design of this jacket is simple and pleasing, and well constructed. The fabric is so lightweight that you can sort of see the down through it, which makes a splotchy appearance. Our reviewers were divided in opinions--some liked it and some did not.
The very lightweight fabric is not as rugged as heavier outer fabrics. It is a similar weight to the Mountain Hardwear Ghost Whisperer, but we found that the Cerium lost down more often than the Ghost Whisperer.
The Cerium SL's tiny zipper is lightweight but not as durable as a plastic one.
This jacket is very simple and straightforward. It packs into a separate stuff sack, which can be hard to keep track of, but is easily repurposed for various gear storing or carrying needs.
This jacket is great as a midlayer insulation. It is a warmer and much more lightweight and compressible alternative to your favorite fleece, and would be great for layering in a dry climate. This is also such a small layer that it is easy to throw it into your messenger bag in case the temperatures drop during your commute.
At $329, this is a pretty pricey piece for layering. We would rather spend the money on a more versatile jacket.
With solid construction, an attractive fit, and sleek design, our reviewers were disappointed not to find more applications for this jacket. The range of uses are very limited for this jacket, but if you're looking for an amazingly light layer to replace a fleece and you travel and adventure mostly in dry climates, this is an excellent down garment for your insulation quiver.