You got to flex it if you want to sex it, baby! The beach is (flex bicep while pointing with thumb) thataway! Sierra Designs has been flexing it for some time now with their sleeping bags. Their 3-season bags use an elastic tape and their ultralight bags use an elastic thread, as does the Flex down jacket. Kudos up front: the Flex uses 100% recycled polyester fibers in the shell fabric.
The Flex isn't designed to be fancy: it's a big two-pound bag o' 750-fill down to keep your core happy, and we had no problem on walkabouts at sub-zero F temps. The Flex does have a few tricks up its sleeves, one of which is the sleeve itself, which uses what SD calls Condor Construction, a long fabric panel – basically no articulated cut – that minimizes hem rise when reaching overhead. The Flex elastic stitching helps with mobility as well, bestowing about 3-4 inches of give where you need it most around the holidays, the gut. Or as the SheFlogger calls it while pointing at me and laughing in front of her friends, the twins.
There are two tricot-lined zippered hand pockets, a tricot chin guard with requisite zipper garage, and a zippered inside left chest pocket with cord port. The left hand pocket has a handy little velcro-flapped credit-card sized pocket-in-a-pocket. The Flex is equipped for serious mountaineering with two large water bottle pockets on the inside down low; some big-mountain jackets only give you one, and you always wish you had another. The only adjustment on the jacket is the two-way adjustable hood, which brings up our only real nitpick, the lack of a hem adjustment. Even though it fits fairly snug by design a high wind is going to get in.