The warmest bag in our Phoenix range, our Flame 400 is a tough and highly insulating sleeping bag for four season camping. The Flame is filled with double layers of 200gsm spiral hollowfibre, a lightweight insulation that can be packed into a stuff sack for easy travel. This is contained within a hard-wearing Ripstop shell that protects it from rips and scratches, and it has an extra tough boot liner, so you can sleep with boots on without damaging the bag. For extreme cold, the Flame can be combined with the Spark, using a Simple hook and loop system, to create a 5 season sleeping bag for below freezing nights.