"What Our Gearhead® Experts Are Saying: ""I wear the Reactor 2. 0 as a daily midlayer—it’s warm without being bulky and breathes well on hikes. The fleece is super soft, and the flatlock seams make it comfortable enough to wear all day."" Sometimes lightweight warmth is all we need to stay comfortable from the trail to town. The Marmot Reactor 2. 0 Fleece Jacket is built with Polartec Classic 100 microfleece, giving us soft, breathable insulation that dries quickly and layers easily. Whether we’re using it as a midlayer under a shell or wearing it on its own during cool evenings, it’s a versatile piece we’ll keep reaching for year-round. Thoughtful details make the Reactor 2. 0 even better. Flatlock seams reduce chafing and allow smooth layering, while a wind flap and chin guard help block out chilly drafts. Zippered chest and hand pockets stash essentials close at hand, keeping us ready for whatever the day brings."