"Women's On® Core Long-T: When the temperature drops but you still want to move light, the On Core Long-T is a women's long sleeve running shirt worth reaching for. Built around a 92% polyester/8% elastane blend, this top stretches with your stride and stays comfortable through cool-weather training runs, brisk morning miles, and the kind of transitional days when a heavy layer feels like too much.The fabric is lightweight and breathable, which helps moisture move away from your skin as your effort builds rather than letting sweat sit. The streamlined fit keeps things out of your way - no bunching, no excess fabric pulling at your arms - so you can focus on the run. It also layers cleanly under a running jacket or vest when conditions call for a little more coverage, making it a practical piece to keep in rotation as seasons shift.Why Our Fit Experts Love It""I grabbed the Core Long-T for an early morning run when it was too cold for a short sleeve but I didn't want to deal with a jacket. It moved really naturally and I didn't notice it once I got going - which is exactly what you want from a long sleeve. The fabric dried out quickly even when I picked up the pace."" - Rachel, Road Runner Sports Fit Expert, Carlsbad, CAWho It's Best ForThe On Core Long-T is a good fit for women who want a lightweight long sleeve running shirt for cool-weather training without the bulk of a heavier layer. If you run in the early morning, train through fall and winter, or just prefer a breathable top that can stand alone or layer under a jacket, this shirt covers that range well. The stretch fabric and streamlined fit make it a natural choice for daily runs, warm-ups, and recovery workouts where comfort and ease of movement matter most. VIP Family members can take the Core Long-T for a 90-Day test drive with our Perfect Fit Guarantee."