The Euler IS is an insulated hardshell jacket for transitional weather, featuring a stowable hood in the collar. Delivering exceptional warmth for weight, the Euler comes with a three-layer GORE-TEX fabric, composite-mapped synthetic insulation for cold and wet weather, and microfleece-lined hand pockets for comfort. Gaskets on the cuffs and hem seal out drafts. What's been updated: Lightweight insulation for improved warmth-to-weight ratio. Updated stowable hood and sleeves with cuff gaskets to seal out drafts.