The Arc’teryx Downword Tank is built for runners who go long, move fast, and don’t stop when the sun goes down. Made from lightweight Phasic FL fabric with a Delta mesh back, it breathes hard and wicks sweat fast, keeping you cool when the pace turns up. Merrow seams and laminated edges mean zero chafe under a pack, while the tailored cut moves with you on technical terrain. A bold reflective logo keeps you visible in low light, and Fair-Trade certification means it’s made with ethics in mind. It’s light, tough, and ready for everything from high-country singletrack to summer ultras.