Built to race. Ready for the rough stuff. The FastRock(TM) Sleeveless is designed to handle high-output efforts on the toughest terrains. It&';s ultra-light, super breathable, and powered by TrailGuard(TM) fabric with highly durable nylon to resist abrasion and reduce pilling from packs. We love it for: trail running and racing Relaxed fit Waist length TrailGuard(TM) fabric: 89% Nylon, 11% Spandex Highly durable nylon body, designed to reduce pilling from wearing running packs Bonded Seams Created with a patented technology, the seams are stronger than traditional bonding and create a sleek, seamless look Rear perf panel for breathability Reflective heat transfers Machine wash cold, tumble dry, don&';t bleach Designed in California, made abroad