Sea To Summit Reactor Midweight Liner Beluga, Short

What Our Gearhead(R) Experts Are Saying:"I use this liner when I want extra warmth without adding bulk to my pack.

The stretch fabric is genuinely comfortable, and the armholes are super practical for late-night camp tasks.

It's also much easier to wash than a full bag, which keeps my sleep system fresher on long trips."We bring along the Reactor Midweight Liner when our nights wander into shoulder-season cold or when we want cleaner, more comfortable sleep on extended trips.

Sea to Summit builds the liner with stretchy knit Thermolite Pro fabric, giving us warmth, mobility, and a soft hand that works inside any sleeping bag.

Available in Short, Regular, and Long sizes, it fits a wide range of heights without restricting movement.

Far Infrared Technology helps trap and reflect body heat, adding noticeable warmth-up to 6degC or 11degF-on colder nights.

Snap-closure arm openings create a practical, free-flow design that lets us sit up, cook, read, or prep gear without fully exiting the bag.

On multi-night trips, the liner helps extend the lifespan of our sleeping bag by reducing the need for frequent washing, and it dries quickly after rinsing.