Reactor Fleeceweight Liner

The Sea to Summit Reactor Fleeceweight Liner boosts warmth for cold conditions while staying packable and easy to care for. Made from Thermolite® Fleece, it stretches as you move and includes armholes for unrestricted comfort—whether you’re a side sleeper or tend to toss and turn. It fits inside any sleeping bag and snaps into compatible Sea to Summit bags for secure placement and easier entry/exit.

Using Thermolite® hollow-core fibres in a grid-fleece construction, the Fleeceweight traps and reflects body heat to noticeably enhance your sleep system’s performance—adding up to 8 °C | 14 °F of warmth with minimal added weight.

The liner is quick-drying and easy to clean, with HeiQ Fresh odour control to stay fresher on extended trips. It also helps extend your sleeping bag’s lifespan by reducing the need for frequent washing, preserving loft and long-term performance.