After years of user feedback, and decades of product testing and tinkering, Outdoor Research is proud to release a completely redesigned bivy program that harnesses the power of innovative technology and ultralight materials to create a bomber shelter in the most compact construction yet. This entire line of bivies weigh significantlyย lighter than their predecessors, and feature a smaller footprint that saves on pack space and weight for convenience, comfort, and effectiveness. Our ultimate goal was to create shelters that weigh less than a single person tent, and the result is a streamlined collection of bivies ideal for thru-hikers, bikepackers, and fastpackers looking to shed ounces and maximize performance. Browse our bivy sack guide below to find out which features, technologies, and shelter choice is right for you. Interstellar Bivy Four-season waterproof, durable, and versatile bivy choice for adventurers looking for a little something extra out of their shelter. Fabric: AscentShellโข Weight: 21ย oz. with pole, 19.2 oz without pole Size: 82โ length x 26โ top width x 17โ top height Best for: Expedition and Extreme Conditions Why youโll love it: Shares the same name as the Interstellar Jacket, Outside Magazineโs Gear of the Year award winner for its supremely breathable and waterproof AscentShellโข technology. Newly designed side entry makes getting in and out of your shelter faster and easier, without any butt-to-ground contact. TPU laminated bivy floor has a bathtub construction that protects you from ground water and rain spray. The fabricโs 40D ripstop also prevents rips and tears. Removable single pole can add headspace or be left behind to save weight. Two stake loops to secure shelter down in high wind. Innovative zipper system uses 6 zipper sliders on mesh and shell to free arms and face, letting you wear your shelter like a jacket for the ability to cook, clean, read, and more โ right from the comfort of bed. Sombrero-style crown provides larger headspace and gear storage. Stargazer Bivy The easiest bivy choice for alpinists, backpackers, and campers who prefer a room (or shelter) with a view. Fabric: AscentShellโข Weight: 19.2oz with pole, 17.2oz without pole Size: 82โ length x 26โ top width x 20โ top height Best for: Fast and Light Why youโll love it: Seam-taped, breathable, and waterproof AscentShellโข technology ensures youโll stay safe from the elements, without compromising breathability. Newly designed side entry makes getting in and out of your shelter faster and easier, without any butt-to-ground contact. TPU laminated bivy floor has a bathtub construction that protects you from ground water and rain spray. The fabricโs 40D ripstop also prevents rips and tears. Removable single pole can add headspace or be left behind to save weight. Two stake loops to secure shelter down in high wind. Enlarged head space and mesh screen to keep out bugs and allow for optimum stargazing. Alpine Bivy GORE-TEX waterproof power for winter mountain missions. Fabric: GORE-TEX Respiration Positive Weight: 20.6oz with pole, 18.7oz without pole Size: 82โ length x 26โ top width x 19.75โ top height Best for: Expedition and Extreme Conditions Why youโll love it: Seam-taped waterproof GORE-TEX Respiration Positive eliminates interior condensation before it has a chance to build up. TPU laminated bivy floor has a bathtub construction that protects you from ground water and rain spray. The fabricโs 40D ripstop also prevents rips and tears. Traditional clamshell opening lets you breathe freely without letting in weather. Removable single pole can add headspace or be left behind to save weight. Two stake loops to secure shelter down in high wind. New Fly Fastener stores shell fabric away from face, and is easily deployed in the event of an unexpected chill or sudden rain. Updated pole positioning keeps bivy erect for ample headroom. Reduced mesh fabric ensures a more taut bug barrier that wonโt sag.ย ย Helium Bivy Award-winning for its ultralight prowess, made even lighter. Fabric: Pertexยฎ Shield+ Weight: 16.2oz with pole, 14.3oz without pole Size: 82โ length x 26โ top width x 19.75โ top height Best for: Fast and Light Why youโll love it: 14% lighter than last seasonโs Helium Bivy. Seam-taped waterproof Pertexยฎ Shield+. Traditional clamshell opening lets you breathe freely without letting in weather. TPU laminated bivy floor has a bathtub construction that protects you from ground water and rain spray. The fabricโs 40D ripstop also prevents rips and tears. Removable single pole can add headspace or be left behind to save weight. Two stake loops to secure shelter down in high wind. New Fly Fastener stores shell fabric away from face, and is easily deployed in the event of an unexpected chill or sudden rain. Updated pole positioning keeps bivy erect for ample headroom. Reduced mesh fabric ensures a more taut bug barrier that wonโt sag.ย Helium Emergency Bivy Under 10 oz. of adventure insurance that packs down to the size of a beer can. Fabric: Pertexยฎ Shield Weight: 9.6 oz. Size: 84โ length x 36โ top width Best for: Emergency Why youโll love it: The lightest weight and smallest packed size we offer in a bivy, the perfect emergency shelter for your 10 Essentials kit. Reusable design and durable material means your investment isnโt wasted after a single use. Seam-taped waterproof Pertexยฎ Shield+. Tube construction with cinch closure to seal out the elements. Browse All Bivy Sacks. *** Photos by Elise Giordano.