What Our Gearhead(R) Experts Are Saying:"The Sonic LS Zip is my first choice for trail runs or fast-paced hikes when layering is key. The lightweight fabric keeps me cool and dry, and the venting zipper is a lifesaver on warm days. I also love the hidden thumbholes-they keep the sleeves in place and add a bit of extra coverage when needed."The Women's Sonic LS Zip is built for active days in the mountains, whether we're chasing personal bests on trail runs or powering through fast-paced hikes. Its ultra-light Motiv(TM) Aero fabric is designed to move with us, offering excellent breathability and moisture-wicking performance to keep us dry and comfortable no matter how hard we're pushing ourselves. Lightweight and packable, this long-sleeve top is perfect for multi-day adventures where space and weight are at a premium. Thoughtful features like a deep YKK chest zip for quick venting and hidden stretch thumb loops for extra sleeve security ensure this layer adapts seamlessly to fluctuating conditions. With odor control treatment keeping things fresh over extended wear, the Sonic LS Zip is our trusted choice for high-output activities in any season.