The L. L. Bean PrimaLoft Packaway Jacket folds down small enough to disappear into a carry-on, then unpacks into real cold-weather protection. PrimaLoft Gold insulation with Cross Core technology uses the same Aerogel developed for NASA to hold heat without adding thickness, so the jacket layers easily under a shell or stands alone in milder cold. A Pertex Quantum shell built from recycled polyester blocks wind and resists weather over sleeves and a full torso, and quilt lines keep the fill in place wear after wear. When the trip's over, the whole jacket stuffs back into its own pocket for the trip home. What Our Gearhead(R) Experts Are Saying:"I packed this instead of a heavier coat for a cold weekend trip, wore it under my shell on the coldest morning, and never once wished I'd brought something bulkier."