What They say: The Thunder Jacket is the pinnacle, über-lightweight mid-layer for outdoor athletes to sport in cold-weather conditions. With a true sweater-like fit, this luxurious 800 fill down jacket is a compact jacket for multi-purpose backcountry endeavors. Fabric: Pertex Quantam 100% nylon ripstop with DWR Avg Weight 380g Insulation: 800 loft Goose Down Length from Center Back: 28 in.  Performance fit Two hand pockets Jacket stows in hand pocket Elastic-bound cuffs Hideaway hem cinch cord

What GearGuys say: It doesnt get much better than this. Pertex Quantum is Oh So Good!! Silky smooth, light-weight and luxurious. Pack it full of the good-stuff, yep lets say it together... Eight Hundred Loft Down. OK, we're getting over-awed with emotion. All the basic details are looked after in spades. It's super-light, the performance fitting means there's no problem fitting it under a shell, it's extremely packable and it stows into its own pocket. The attention to detail with the Summit Series embossing of the lining is also a neat trick. Ask yourself  'Am I worth it?' We think there is no question.