The 686 Smarty 3-in-1 Framework(TM) Jacket runs on 686's original SMARTY(R) detachable layering system, so the shell and the removable Rodeo Puffer Vest liner work as two genuinely separate pieces of gear built to pair. A 3-layer infiDRY(R) 20K face fabric handles 20,000mm of waterproofing and 15,000g of breathability entirely on its own, so the shell alone covers a warm spring lap without the liner along for the ride. When temperatures drop, the 200g infiLOFT(R) insulated liner zips back in for real cold-weather warmth instead of relying on a single fixed layer to cover every condition. A helmet-compatible hood, removable powder skirt, and Pant Jacket Connect(TM) system round out a jacket built to handle a full storm cycle without packing a second layer. What Our Gearhead(R) Experts Are Saying:"I skied the shell alone on a bluebird afternoon and zipped the puffer back in that same night for a much colder morning session, and neither piece ever felt like a compromise on its own. The liner works fine as a standalone piece off the mountain too, so it's not just dead weight riding along in a pack."