Maximumwarmth-to-weight.

What It Is

The highest thermal performance per gram in the Thindown line.

Fill power is the measure of how much space one ounce of down occupies — a higher number means more trapped air per gram, and more trapped air means more warmth. Thindown Ultra is built with premium-grade fill power goose down engineered for the conditions where warmth is not optional.

In a continuous sheet format, the advantage compounds. There's no quilt-induced compression to reduce effective loft. No cold channels where two chambers meet. The down clusters are fixed in position across the full panel, delivering maximum thermal performance.

Weight range is 30–150gsm — lighter than Core at equivalent warmth. For alpine and expedition programs where every gram on the pack list is accounted for, Ultra provides genuine warmth-to-weight optimization that no other insulation format can match.