Temperature Rating: 14°F to 5°F (-10°C to -15°C)Many view the Softie 12 Osprey the ultimate four season synthetic fill sleeping bag available. Since 1987 it has been setting the standard for winter pack size performance for others to follow. Those who know about the Softie? 12 Osprey have either used one or wished they had one. Used from the heights of the Scottish mountains to the bottom of your snow hole. The Softie? 12 Osprey like many of our other Sleeping Bags in the Softie? Original Series have been assigned a NATO Stock Number.