Engineered for intense cold-weather backpacking and demanding winter ski touring expeditions, the Sea To Summit Thermolite Reactor Fleeceweight Sleeping Bag Liner is a highly efficient thermal booster designed to significantly increase your sleep system’s temperature rating.

Utilising innovative Thermolite hollow-core yarns structured in a specialised grid fleece pattern, this liner expertly captures and retains body heat to provide maximum thermal efficiency with minimal weight. Its high-performance stretch knit construction, ergonomic technical shape, fitted hood, and shaped arm openings work together to guarantee complete freedom of movement without adding unwanted bulk. Integrated snap attachments seamlessly secure the liner inside compatible Sea To Summit sleeping bags, preventing twisting and simplifying entry and exit during the night.

Highly practical and easy to clean, this quick-drying liner features advanced HeiQ Fresh odour control to maintain long-lasting freshness on extended backcountry trips. Crafted with sustainability in mind from recycled fibres and bluesign-approved materials, it acts as a protective barrier to reduce how frequently you need to wash your down or synthetic sleeping bag, thereby extending its lifespan.

During milder summer conditions, it can be used as standalone lightweight sleeping bag, offering versatile, year-round utility for outdoor enthusiasts.

Key Features:

  • Regular Size: With a length of 193cm, recommended for users with a maximum height of 185cm.
  • Thermal Performance: Premium Thermolite hollow-core fibres knitted into a grid fleece structure trap insulating warm air to deliver substantial thermal warmth with minimal weight.
  • Ergonomic Design: Features a contoured technical shape, a snug fitted hood, and shaped arm openings that provide optimal insulation coverage without feeling restrictive.
  • Unrestricted Comfort: Built with a flexible stretch knit material that expands naturally as you shift, ensuring flexible, unhindered movement throughout the night.
  • Sleep System Integration: Integrated shoulder snap attachments secure the liner directly inside Sea To Summit sleeping bags for effortless entry and exit.
  • Odour Management: Treated with biocide-free HeiQ Fresh odour control technology to neutralise unpleasant odours over multi-day trips.
  • Eco-Conscious Build: Fabricated using certified recycled fibres and bluesign approved materials, minimising environmental impact without sacrificing performance.
  • Easy Maintenance and Protection: Exceptionally easy to clean and quick-drying, serving as a washable liner that protects your primary sleeping bag from dirt and body oils.
  • Multipurpose Functionality: Adaptable for all seasons—boosting sleeping bag warmth during cold-weather backpacking and winter ski touring, or can be used as standalone lightweight sleeping bag in warm weather.
  • Stuff Sack Included: For safely storing the liner without harming its insulating properties.

 

When paired with a quality sleeping bag and insulated sleeping mat, the Sea To Summit Thermolite Reactor Fleeceweight Sleeping Bag Liner can boost the thermal performance of your sleep system by up to 8°C (14°F).
While highly effective for cold-weather adventures, the Sea To Summit Thermolite Reactor Fleeceweight Sleeping Bag Liner Long is slightly bulkier due to its fleece construction, making it best suited for winter backpacking, ski touring, and trips where extra insulation takes priority over extreme packability.
The Sea To Summit Thermolite Reactor Fleeceweight Sleeping Bag Liner features shoulder snap attachments designed to connect directly into compatible Sea To Summit sleeping bags, preventing shifting and making entry and exit easy.

Brand : Sea To Summit

SKU: S2ST-053402

Model # : 053402

Barcode : 9327868169726  (AD-2)

Shape : Mummy

Weight : 400g

Dimensions : 193 x 80cm

Packed Size : 25 × 15 × 15cm

Recommended User Height : 185cm

Liner Material : 100% Post-Consumer Recycled Polyester

Stuff Sack Material : 100% Polyester

Free shipping on orders over $140 to Australia*
Shipping on small orders (under $140) only $9.95
Shipping on all orders to NZ only $9.95
Express shipping to Australia & NZ only $15

Standard Shipping (AU) – FREE on orders over $140 and $9.95 on orders under $140. Orders are dispatched within 1 business day. Click here for shipping delivery times

Select ‘Standard Shipping – Auspost Only’ if you would prefer your parcel is sent with Auspost. Otherwise it will be shipped with any of our available carriers. Auspost Only shipping is not available on some very heavy/bulky orders.

Express Shipping (AU/NZ) – Need it faster? Express Shipping is available for $15. Express Shipping is not available on heavy/bulky orders. Orders placed before midday on business days are usually dispatched same day (otherwise within 1 business day). Delivery times in the table below.

Click and Collect – Shop online and collect in our Milton, Brisbane store, free for all orders. Orders are usually ready within 2 hours (during opening hours). Click here for address and opening hours.

Terms and conditions apply, click here for a full overview of our shipping policies

Manufacturing defects covered, replaced or repaired if soon after purchase.

  • If you have selected the wrong product/size for you, or want to exchange/return for any reason except for warranty or our error, this is referred to as a 'change of mind' return.
  • Not all products are eligible for change of mind returns (click here for excluded products).
  • Once you submit a Return Request, we will provide return instructions via email (along with a prepaid return label if applicable). Please wait to receive this before returning any items (Try 2 Anything excluded)
  • Change of mind returns can be resolved by your choice of exchange, full store credit, or a refund. Refunds are subject to a $19.95 admin fee.

For a full overview of our returns and warranty policies, see Returns and Warranties

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