Ultralight Features. Ultralight Price Tag. Built with synthetic insulation and lightweight material typically reserved for a higher price point, the Synthesis Sleeping Bag packs light but hits heavy with its feature set. A dual zipper system makes getting in and out a breeze and gives you room to move about, while the self sealing foot vent lets you vent heat with ease. Features: Synthetic insulation provides lofty warmth, even when wet Dual zipper system for ease of use Patented self-sealing foot vents for fast and easy ventilation Draft dodger collar helps prevent drafts 20D nylon fabric for lightweight versatility Materials: Insulation: Synthetic Shell Fabric: 20d Nylon ripstop Liner Fabric: 20d Nylon Taffeta Technical Specifications: Long EN Limit Temp Rating: 25F / -4C EN Comfort Temp Rating: 35F / 1C Fill Weight: 25oz / 720g Minimum Weight: 2lb 6oz / 1080g Fits Up To: 6' 6" / 198 cm Length: 82in / 208 cm Shoulder Circumference: 64" / 163 cm Hip Circumference: 58" / 147 cm Footbox Circumference: 42" / 107 cm Mesh Stoarge Bag Size (LxW): 20 x 12" / 51 x 31 cm Stuff Sack Size (L x W): 15 x 7.5" / 38 x 19cm Source: Imported Sierra Designs Synthesis 35 Degree Sleeping Bag - Long