The Sea to Summit Thermolite Reactor is a high-performance sleeping bag liner designed to increase warmth by up to 8°C (14°F). It is constructed from 80g​/​m² Thermolite fabric, featuring hollow-core fibers that trap heat efficiently while maintaining excellent breathability. The liner features a mummy shape with a tapered box foot and a drawcord hood with a mini cord lock to maximize thermal efficiency. It functions as a lightweight layer for warm weather or as a performance-boosting liner for cold-weather camping. Technical Specifications: Weight: 248g (8.7 oz). Dimensions: 210cm x 90cm. Material: 100% Thermolite polyester. Includes a lightweight Ultra-Sil stuff sack for compact storage.