The Roark Grid Lock Fleece Jacket pairs recycled polyester fleece with a half-zip mock neck and underarm gussets, so the fabric that keeps the chill off can also open up once the effort ramps up. A zippered chest pocket holds keys or a phone secure through a run, and flatlock coverstitched seams keep the fit smooth against the skin. The fleece prioritizes movement over pure warmth. What Our Gearhead(R) Experts Are Saying:"Three miles into a tempo run and the temperature swings from cold start to sweaty legs, I unzip the half-zip and feel the underarm gussets do the rest. The heat vents out before it builds into overheating, so I never have to stop and pull the jacket off."