Sea to Summit Reactor Extreme Liner Thermal Sleeping Bag Liner

The Sea to Summit Reactor Extreme Liner is engineered for adventurers tackling cold-weather missions where warmth, comfort, and adaptability are crucial. Crafted with advanced Thermolite® Pro fabric, this liner features infrared-absorbing ceramic pigments that capture and retain your body heat, boosting your sleeping system’s thermal efficiency.

Perfect as a standalone layer on warmer nights or as a powerful cold-weather upgrade inside your sleeping bag, its soft, stretch-knit construction ensures excellent moisture management and freedom of movement. The addition of a drawcord footbox allows for both ventilation and mobility—yes, you can even walk around camp while staying cozy inside your liner.

Whether you're thru-hiking at high altitude, winter camping, or looking to extend the life and warmth of your sleeping bag, this liner is a game-changer for serious outdoor sleep systems.