Trail Running PERTEX 3L ultra-lightweight waterproof fabric for flexible weather protection. Lightweight design with no wearing burden, easy to carry and stow in a trail running vest. Underarm AAC LITE structural ventilation system increases breathability by 35%, rapidly wicking sweat for lasting comfort. Ergonomic 3D tailoring in arms and shoulders reduces seam weight and enhances freedom of movement; elbow articulation allows natural arm swing. Back expansion compatible with trail running vest for pack-over wearing. Trail-specific hood-collar structure with low front collar for improved dynamic fit without blocking vision. Elastic cuffs and hem effectively seal out wind and rain for trail-running postures. Fit: Athletic