We discovered 37.5™ Technology (formerly Cocona) insulation while looking for an alternative to goose down, and, so far, we're impressed.
This is how it works: Activated carbon derived from coconut husks is blended with recycled polyester. This, in turn, increases the surface area of the insulation allowing it to dry faster and resist odors (you can imagine a pool of water takes longer to evaporate than if you spread the same liquid across a counter), and carbon, being dark in color, is able to absorb more heat.
In the end, you have a garment that retains heat, dries faster, resists odors and provides a higher warmth-to-weight ratio than other synthetic insulations. So what's the problem? We haven't found one yet. But the lingering question remains: Is 37.5 insulation as effective as goose down? Is it more sustainable? Both are still up for discussion, but we've found that our jackets and hoodies with 37.5 insulation are a great addition to any cold-weather wardrobe.