The new Winterlite sleeping bag has a hydrophobic and windproof shell, which keeps the down dry and heat inside. 

Available in three temperature ratings, depending on the severity of the weather and the temperature - and the needs of the sleeper: 

• Winterlite -6 (+21F)
• Winterlite -16 (+3F)
• Winterlite -42 (to minus 44F)

Winterlite, like all Exped sleeping bags, is feature-rich - the details count and they add up to an amazingly warm and efficient sleeping bag for the most severe conditions. 

• Radical differential cut - down chambers on top reach to the ground to enfold the sleeper in unrestrained insulation
• Freestanding, multi-chambered, three dimensional footbox - no toes poking through the down chambers = warm feet!
• Hydrophobic and windproof shell - condensation, spilled soup, melting spindrift are kept away from the down
• Plush draft collar - adjustable around the neck to add insulation at this critical area and reduce heat loss due to movement within the bag
• Roomy, sculpted hood - snugs around the head when needed, opens when venting is necessary and accomodates an EXPED pillow
• Swift adjustment of the hood with SidePull closure - easy to operate in the dark 

Here's a video describing the features, suggested usage and details: