The Reactor Midweight enhances your sleep system with advanced Thermolite Pro fabric. Infrared-absorbing ceramic pigments and hollow-core fibers trap body heat, adding up to 6C|11F to a sleep system with minimal bulk. Stretch-knit fabric and arm openings allow unrestricted sleep, making it a great fit for any shape sleeping bag. Quick-drying and easy to clean, it features HeiQ Fresh odor control and helps extend your sleeping bags lifespan by reducing wash frequency. Features Boosts Sleep System Warmth Thermolite Pro uses Far Infrared technology and hollow-core fibers to trap and reflect body heat without extra bulk 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 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