The ultimate super-lightweight and compact high performance sleeping bag.Ultra-light and technical, our Spark™ Series bags are designed to keep you as warm as possible while minimizing packed weight and size.The Spark™ Series spans everything from an ultralight liner to an expedition weight mid-winter bag. While the end usage is very different, they reflect a design ethos of matching weather conditions to the lightest bag possible.The secret to the impressive performance is a combination of premium materials and careful design. The RDS 850+ Loft premium goose down, light-gauge #3 YKK zip and high performance 10D Nylon shell and 7D lining fabrics, set the stage for superior performance. These materials are combined with a contoured mummy design for efficient insulation, and that mummy design is then tweaked for each model to best fit the use scenario.Our ULTRA-DRY Down™ water-repellent treatment protects the down from external moisture and condensation from the inside of the bag, virtually eliminating the negative effects moisture has on down. All Sea to Summit Down Sleeping Bags use Responsible Down Standard (RDS) certified down.The ULTRA-DRY Down™ protection also makes the Spark™ an impressive hard-alpine or adventure racing bag, where every gram is counted and down has never been a viable option.Features• Vertical box baffles in the torso area accommodate extra down and boost warmth around the core, vertical baffles in chest optimize position of down to prevent it moving during use• Lower part of the bag uses a sewn through horizontal baffle construction to minimize weight• ½ zip with two sliders aids access and allows ventilation from mid-section of bag• Updated sizing provides extra room for both shoulders and hips while still maintaining insulation efficiency• Draft tube prevents heat loss through the zipper• Includes hood draft collarSpecifications• Max user height: < 192 cm / 6'4''• Girth:Shoulder: 158 cm (62“)Hip: 138 cm (54“)Foot: 94 cm (38“)• Fill weight: 12 oz / 345g• Weight: 1 lb 4 oz / 554g• Temperature:Comfort: 38°F / 4°CLower limit: 28°F / -2°CExtreme: 0°F / -18°C.