Forming a protective barrier between our funky bodies and our expensive sleeping bags, the Therm-a-rest Synergy Sleeping Bag Liner extends the life of our sleep system. The soft-knit polyester is soft against our skin and absorbs the sweat, grime, and oils that would otherwise seep into our bag, decreasing its loft and sapping away its insulating power. For a few extra dollars and ounces, this liner may add years to our sleeping bag and also add up to 5 degrees of warmth to it, too.
