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: Regular EN Limit Temp Rating: 25F / -4C EN Comfort Temp Rating: 35F / 1C Fill Weight: 23oz / 662g Minimum Weight: 2lb 4oz / 1021g Fits Up To: 6' 0" / 183 cm Length: 76in / 193 cm Shoulder Circumference: 62" / 152 cm Hip Circumference: 56" / 142 cm Footbox Circumference: 40" / 102 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 - Regular