The lightest bag in the Phoenix range, the Spark 150 is a lightweight and tough sleeping bag for two season camping. The Spark is filled with 150gsm spiral hollowfibre, a lightweight insulation that weighs only 1.1kg and 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.. Comfort and Compression. The mummy shape of the sleeping bag is designed to help trap heat inside, keeping you warm and comfortable throughout the night. This shape also helps to reduce the overall weight and size of the sleeping bag, making it easier to pack and transport. The Phoenix Spark 150 comes with a compression stuff sack, which allows you to pack the sleeping bag down to a smaller size, making it easier to transport. The sleeping bag also features an insulated zip baffle that prevents heat loss through the zipper. This fea