"What Our Gearhead® Experts Are Saying: ""This vest is my go-to for summer trail runs and hot weather hikes. It’s incredibly breathable, dries super fast, and I’ve never had issues with chafing under my running vest—plus the laser-cut vents really help when it gets steamy."" Designed for big efforts in hot weather, the Rab Sonic Ultra Vest is built to keep us cool, dry, and moving fast. Whether we're chasing PRs on dusty trail climbs or powering through technical descents, this ultralight running top regulates temperature and eliminates distractions. Made from Motiv™ Aero fabric with a subtle mesh structure, it wicks moisture in real-time and dries in a flash. Laser-cut vents under the arms and behind the neck dump excess heat, while the slim fit and strategic seam placement reduce friction—even under a hydration pack. With minimal bulk and maximum breathability, this is the layer we count on when the pace is high and the temps are higher."