The Coefficient is a lightweight and technical fleece, constructed from a combination of polyester/nylon with a bit of elastane for some stretch and mobility. Its grid pattern raises the fabric away from the skin, providing excellent wicking performance through the thin and air-permeable design. This makes it awesome for cold days when you're working up a sweat and need a layer to stay warm — think long hikes, climbing objectives, and trail runs.
The Coefficient is also one of the lightest fleeces we tested. Its slim-fitting construction is low bulk and easy to layer, especially beneath a backpack or climbing harness. The thumb holes are functional for additional warmth and also make the Coefficient easy to layer under thinner puffy jackets within your technical kit. The low-profile design also makes it more packable for those seeking a layer of protection for alpine objectives where every ounce is a consideration. And while some may not love the lack of hand pockets, our testers love the streamlined construction and found it easy to stow essentials in the zippered chest pocket.
Our tester remarked that the fleece is long in the torso and arms, which is great for activities where you'll be reaching over your head, since it doesn't expose your midsection or forearms. She also appreciated that the forearms are fitted yet not tight.
While some fleece jackets in our comprehensive review prioritize comfort, we're sorry to report that the Coefficient isn't one of them. Some online reviewers report a scratchy fabric; we don't exactly agree, however, the interior grid pattern does sacrifice some next-to-skin comfort in exchange for technical performance.
The Coefficient is not great for standalone warmth, but that's not what it's designed for. It excels during cold-weather exercise, when you need a little something extra but don't want sweat to build up and cool you down, but if you're looking for a fleece to keep you toasty during chilly fall temps, strolling around town, you'll probably want to choose a warmer layer.
The Coefficient is an awesome lightweight layer that's geared more towards high output performance rather than a cozy standalone jacket for hanging around the fire; however, it's among the more expensive jackets that we've tested. If you're after a niche technical fleece jacket design, this may be a good choice for you. Overall, we like it, but there are more affordable technical jackets in our review that we'd suggest looking into.
| Awards | |
|---|---|
| Price | $199 List Check Backcountry (on sale!) |
Overall Score  |
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| Star Rating | |
| Bottom Line | A lightweight and technical fleece that's perfect for versatile outdoor pursuits, thanks to its streamlined and breathable construction |
| Pros | Large zippered chest pocket, stretchy fabric, helmet-compatible hood, lightweight and breathable, slim fit, hip length and thumb holes great for added coverage and easy layering, fast drying |
| Cons | No hand pockets, interior fleece lacks softness, fabric smelly over time, pricey |
| Rating Categories | Black Diamond Coeffi... |
| Warmth (25%) | |
| Comfort (25%) | |
| Breathability (20%) | |
| Layering Ability (15%) | |
| Weight (15%) | |
| Specifications | Black Diamond Coeffi... |
| Type | Lightweight |
| Main Material | 51% polyester/36% nylon/13% elastane |
| Number of Pockets | 1 chest |
| Features | Low profile hood, Polartec Power Dry fleece |
| Measured Weight (Size Tested) | 8.9 oz (Size S) |
| Hood Option | Yes |
| Cuff Construction | Elastic cuff with thumb hole |
