Men's Insulated Jackets

Down performs best in dry cold conditions below freezing. That’s why we test ours regularly in the tundra of Iceland and on expeditions inside the Arctic Circle where temperatures can drop below -30 °C. At these temperatures you are less likely to experience sustained or heavy rainfall and so there is less risk of the down wetting out and having its insulation compromised. The Bastion Down Jacket, built for arctic expeditions and high-altitude mountaineering, uses 900 fill power goose down, the highest in the ThruDark range. On the other hand, if conditions are wet as well as cold, synthetic insulation is the more reliable choice because it does not clump when damp.

Consider three things: fill power, fit and conditions. Higher fill power delivers more warmth per gram. Here a 900 fill power (Bastion Down Jacket) suits extreme cold and high altitude where a 750 fill (Breach Jacket) handles harsh conditions at lower elevation. If you are layering over mid-layers, a longer cut like the Patriot Jacket accommodates the bulk. If your environment involves any moisture, synthetic insulation is the more reliable choice. Down excels in dry cold. Match the jacket to your actual environment.

Yes. Fill power measures loft: how much space one ounce of down occupies when it expands. Higher fill power means more trapped air per gram, which means more warmth at less weight. 800 fill power is meaningfully warmer per gram than 600. ThruDark's Bastion Down Jacket uses 900 fill power, the highest in the range, built specifically for arctic conditions and extreme altitude where that thermal margin is not a comfort consideration. It is a necessity.

Goose down typically achieves higher fill power and loft than duck down, making it more thermally efficient gram-for-gram. In practical terms, a goose down jacket delivers the same warmth in a lighter, less bulky package. ThruDark's down jackets all use goose down: 750 fill power in the Patriot Jacket, 800 in the End of Days Parka, 900 in the Bastion Down Jacket. In dry cold conditions both perform well. The gap widens in extreme cold, where quality goose down holds a clear advantage. Do not confuse down with feathers, down is the soft, fluffy undercoating on a duck or goose that provides warmth, feathers are the bird’s outer plumage which have evolved to protect and are therefore heavier and more structured.

Down jackets are not typically designed to be waterproof, this is because down clumps when wet which compromises its ability to insulate. ThruDark down jackets have their outer fabric treated with a durable water repellent, which will shed light rain and protect the down for a short while. However, if your endeavour involves heavy rain or sustained exposure to the elements, layer a down jacket beneath a hardshell such as the Aigis Jacket for the best protection.

Synthetic insulation is best for wet conditions. Down loses its loft when wet, which significantly reduces its warmth. Synthetic insulation retains most of its thermal performance even when damp. ThruDark's Engage and Ithax Jackets are built with synthetic insulation for exactly this reason: designed for dynamic outdoor pursuits where rain, exertion and sweat are factors. Down is the superior choice for static activity in dry cold, where its warmth-to-weight advantage is unmatched. Choose a synthetic insulated jacket for wet cold environments and/or faster paced activities like hiking or climbing.

None of those terms determines warmth on its own. "Puffer" describes construction style. "Down" describes the fill material. "Insulated" covers both down and synthetic options. What determines warmth is fill power, fill weight and construction quality. ThruDark's warmest jacket by fill power is the Bastion Down Jacket: 900 fill power goose down, built for arctic expeditions. The End of Days Parka, at 800 fill power with added Polartec® fleece, is built to the same standard for the harshest conditions.

Down delivers superior warmth-to-weight in dry cold. It compresses well, and its high fill power means exceptional thermal performance with minimal bulk. Synthetic insulation is the better choice in wet conditions: it retains warmth when damp and recovers faster. ThruDark builds both. The Bastion Down Jacket (900 fill power) and End of Days Parka are designed for dry extreme cold. The Engage and Ithax Jackets use synthetic insulation, built for variable conditions and high-output pursuits where moisture is a factor. Know your environment and your activity before you choose one or the other.