Midweight Insulation

Midweight insulation is built for movement and versatility. It keeps you warm on cold approaches or rest breaks but won’t overheat when you’re working hard. Heavyweight insulation, like expedition parkas, is designed for static warmth in frigid conditions. If you’re climbing or moving, midweight is the sweet spot.

Synthetic insulation performs better in damp or mixed conditions and is easier to maintain. It’s the go-to choice for most midweight pieces, like the Atom Hoody or Nano Puff. Down offers better warmth-to-weight but loses loft when wet, so it’s typically reserved for heavier, cold-weather layers.

It should feel trim but not tight, allowing room for a baselayer and lightweight insulation underneath and a shell on top. A closer fit helps retain warmth and keeps the jacket from bunching when layered, while articulated sleeves and stretch fabrics maintain mobility.