The Sonic Ultra Vest is designed to offer maximum comfort on mountain runs and fast hikes in the heat. Designed with a slim-fit and low profile, carefully positioned seams, it minimises friction over long distances.Built with ultralight Motiv™ Aero fabric, the Sonic Ultra Vest is fast-drying, quick-wicking and highly breathable. With its subtle mesh structure, the fabric wicks moisture away from the skin, keeping you dry on steep climbs. The laser cut vent holes in high heat areas dump heat quickly from under the arms and the back of the neck. Designed to fit comfortably with a running pack, it’s ideal on its own for running in hot climates, or for layering over as you climb to higher altitudes and exposed terrain.Details Fit: Slim Centre back length: (Size S): 64cm / 25.2inch Weight: 47g/1.7oz (Size 10) Motiv™ Aero single jersey fabric with subtle mesh structure (85gsm) with odour control treatment Racerback design Lightweight fast wicking fabric with bulk yarn technology Microactive seams are strong and soft inside for comfort Lazer cut vent holes in back of the neck Split hem detailing with reflective bar tack Reflective branding Hydration pack ready comfort fit Minimized seams positioned for reduced chafing over long distances 100% polyester Centre back length (Size 10): 64cm / 25.2inch