The Therm-a-Rest Saros 20 Sleeping Bag is a three-season bag which has eraLoft insulation ThermaCapture seams and can be integrated to your Therm-a-Rest mat for optimal comfort and efficiency making this a fantastic choice of sleeping bag for spring through to autumn The eraLoft insulation is a compressible synthetic insulation that repels water and possesses excellent termperature regulation thanks to the hollow fibres used It also features ThermaCapture Seams to boost the bag s warmth without adding bulk The Saros has a toe-asis foot warmer which is a baffled pocket of insulation which helps rapidly warm cold feet inside the ergonomic footbox The SynergyLink Connectors also integrate the Saros with your mattress to ensure superior comfort with efficient warmth and the freedom to move as you like it also has quilt and blanket loops too if you want to layer a Therm-a-Rest quilt or tech blanket for the best night s rest possible