Optimized for minimal weight and maximum warmth, the Reactor Lightweight enhances sleep system performance with advanced ThermoliteA(R) Pro fabric, which uses infrared-absorbing ceramic pigments and hollow-core fibers to trap body heat. Adding up to 4AdegC|7AdegF of warmth with minimal bulk, it&&';;s ideal for ultralight expeditions. Stretch-knit fabric and articulated arm openings ensure unrestricted mobility. Treated with HeiQ Fresh odor control, it&&';;s quick-drying, machine washable, and helps prolong your sleeping bag&&';;s lifespan by reducing wash frequency. Best Use: Backpacking, Cycle touring, Paddle touring Features Lightweight and insulative, ThermoliteA(R) Pro technology with hollow-core fibers and infrared-absorbing pigments enhances warmth with minimal pack size Freedom to Move - Stretch-knit and shaped arm openings allow unrestricted movement, providing natural comfort throughout your sleep Technical Shape and Hood - Ergonomic design with a fitted hood delivers optimal warmth and comfort without extra weight or bulk Fits any sleeping bag - Stretch fabric means the Reactor Liner fits any shape of sleeping bag Stay Fresh Longer - HeiQ Fresh odor control technology keeps the liner fresh after extended use Sleep System Integration - Snap connectors at the shoulders easily pair with Sea to Summit sleeping bags for quick, hassle-free entry and exit Easy to Keep Clean - Machine washable construction simplifies care and reduces wear on your sleeping bag over time Lower Impact Materials - Crafted with certified recycled fibers and bluesign APPROVED materials to minimize environmental impact Tech specs Regular Weight 9.0oz Dimensions 76.0 x 31.5 in Packed Size 3.9 x 7.1 x 3.9 in Material(s) 100% Post-Consumer Recycled Polyester; Stuff Sack: 100% Polyester