Optimised for minimal weight and maximum warmth, the Sea to Summit Reactor Lightweight Sleeping Bag Liner boosts your sleep system performance without adding unnecessary bulk. Built with advanced Thermolite® Pro fabric, it uses infrared-absorbing ceramic pigments and hollow-core fibres to trap body heat and add up to 4°C of extra warmth. The stretch-knit construction and shaped arm openings allow natural movement through the night, while the ergonomic hood enhances thermal efficiency without feeling restrictive. Treated with HeiQ Fresh odour control, the Reactor Lightweight stays fresher for longer, dries quickly, and helps extend the life of your sleeping bag by reducing wash frequency. Designed for backpacking, cycle touring, and paddle touring, it’s a compact, technical liner for ultralight adventures.

Sea to Summit Reactor Lightweight Sleeping Bag Liner – Key Features

• Thermolite® Pro insulation: Hollow-core fibres and infrared-absorbing pigments enhance warmth with minimal pack size.
• Adds warmth: Increases sleeping bag performance by up to 4°C.
• Stretch comfort: Stretch-knit fabric fits any sleeping bag shape and allows unrestricted movement.
• Technical hood design: Ergonomic hood improves warmth without adding bulk.
• HeiQ Fresh odour control: Helps keep the liner fresh after extended use.
• Sleep system integration: Shoulder snap connectors pair with compatible Sea to Summit sleeping bags.
• Machine washable: Easy care construction reduces wear on your sleeping bag.
• Lower impact materials: Made with certified recycled fibres and bluesign APPROVED materials.

Specifications – Reactor Lightweight Sleeping Bag Liner

• Best Use: Backpacking, Cycle Touring, Paddle Touring
• Type: Thermal Liner
• Material(s): 100% Post-Consumer Recycled Polyester
• Stuff Sack Material: 100% Polyester
• Temperature Boost: Up to +4°C

Available Sizes

• Short
  Weight: 235 g
  Dimensions: 178 x 80 cm
  Packed Size: 10 x 18 x 10 cm
  Fits Up To Height: 170 cm
• Regular
  Weight: 255 g
  Dimensions: 193 x 80 cm
  Packed Size: 10 x 18 x 10 cm
  Fits Up To Height: 185 cm
• Long
  Weight: 270 g
  Dimensions: 206 x 80 cm
  Packed Size: 10 x 18 x 10 cm
  Fits Up To Height: 198 cm

Imagine the comfort of a warm cocoon in the heart of the wilderness. That's what the Sea to Summit Reactor Fleece Sleeping Bag Liner - Compact Mummy w/ Drawcord offers. Its thermal boost feature is designed to retain heat and warmth, making it the heart of your sleep system. The liner uses hollow-core Thermolite® EcoMade fibres in a grid-pattern fleece for maximum warmth retention. The drawcord footbox can be opened or closed for optimal comfort and integrates perfectly with the footbox of Sea to Summit's Free-Flow Zip system. The liner also features HeiQ Fresh odour control technology, ensuring it stays fresh even after extended use. Its mummy shape is designed for maximum thermal efficiency and includes shoulder zippers and footbox drawcord for additional temperature regulation. Best of all, the Sea to Summit Guarantee is offered for the lifetime of this product, giving you peace of mind for your outdoor adventures.

Sea to Summit Reactor Fleece Sleeping Bag Liner - Compact Mummy w/ Drawcord Features:

• Thermal Boost: The Reactor liner provides a thermal boost to retain heat and warmth, extending the performance of your sleeping bag and sleeping mat in the coldest of conditions.
• Hollow-core Thermolite® EcoMade Fibres: These fibres are used in a grid-pattern fleece for maximum warmth retention.
• Drawcord Footbox: This feature can be opened or closed for optimal comfort and integrates perfectly with the footbox of the Free-Flow Zip system in select Sea to Summit sleeping bags.
• HeiQ Fresh Odour Control Technology: This technology helps keep the liner fresh even after extended use.
• Mummy Shape Design: The liner is designed for maximum thermal efficiency and includes shoulder zippers and footbox drawcord for additional temperature regulation.
• Sea to Summit Guarantee: This guarantee is offered for the lifetime of the product.

The Sea to Summit Breeze Sleeping Bag Liner – Regular RCS delivers breathable comfort for warm-weather adventures and lightweight travel. Designed for backpacking, cycle touring and paddle touring, this cooling liner blends COOLMAX® EcoMade polyester with biobased Tencel Lyocell fibres to wick moisture and regulate temperature through the night. The super-stretch knitted construction allows natural movement whether you sleep still or tend to toss and turn. Easy to wash, quick drying and treated with HeiQ Fresh odour control, it also helps extend the lifespan of your sleeping bag by reducing wash frequency.

Sea to Summit Breeze Sleeping Bag Liner – Regular RCS Key Features:

• Cooling comfort: COOLMAX® EcoMade and Tencel Lyocell fibres work together to wick moisture and regulate temperature on warm nights.
• Stretch fit design: Knitted stretch fabric adapts to any sleeping bag shape and allows unrestricted movement.
• Odour control: HeiQ Fresh technology keeps the liner feeling fresher for longer on multi-day trips.
• Ventilated footbox: Mummy version includes a drawcord footbox for improved airflow and comfort.
• Climate Control openings: Technical hood and shoulder openings maximise mobility without adding unnecessary weight.
• Protects your sleeping bag: Reduces dirt and body oils reaching your bag, helping preserve loft and performance.
• Easy care: Machine washable and quick drying for low-maintenance travel.
• Responsible construction: Made with certified recycled materials and bluesign APPROVED components.

Specifications – Regular

• Best Use: Backpacking, Cycle Touring, Paddle Touring
• Type: Cooling Liner
• Weight: 275g (9.7oz)
• Dimensions: 205 x 80 cm
• Packed Size: 10 x 18 x 10 cm
• Fits Up To Height: 185 cm
• Materials: 70% Polyester, 30% Tencel Lyocell

Lightweight, compact and breathable, the Regular Breeze Liner is a versatile sleep solution for warm conditions and a practical way to keep your sleeping bag cleaner for longer.

The Sea to Summit Lightweight Compression Sack – 5L – Surf Blue is a compact and durable solution for organised pack storage on backpacking and travel adventures. Made from bluesign APPROVED recycled 70D nylon with a PFC-free DWR finish, it offers an excellent strength-to-weight ratio while keeping soft gear neatly compressed. Designed for internal pack organisation, it can reduce contents to roughly one-third of their original volume, helping you maximise valuable pack space.

Sea to Summit Lightweight Compression Sack – 5L – Surf Blue Key Features:

• Efficient compression: Reduces soft items to approximately one-third of their packed size.
• Lightweight durability: Recycled 70D nylon with 2,000mm PU coating for added weather resistance.
• PFC-free DWR finish: Water resistant fabric suitable for internal pack storage.
• Three-strap system: XS and S sizes use three compression straps for weight savings and easy access.
• Flip-top lid: Prevents strap tangling and keeps closure secure.
• White interior coating: Improves visibility when locating gear.
• Base grab handle: Reinforced nylon webbing for easy handling.

Specifications – 5L

• Best Use: Pack Organisation
• Capacity: 5 Litres
• Weight: 68g
• Dimensions: 15.2 x 15.2 x 29.6 cm
• Closure: Drawstring with compression straps
• Waterproof? Water resistant only – seams are not tape sealed

Compact and practical, the 5L Surf Blue Compression Sack is ideal for compressing clothing layers or lightweight insulation inside your pack.

The Sea to Summit Evac Compression Dry Bag HD – 8L – Jet Black is a rugged waterproof compression sack built for demanding backpacking, bikepacking and motorcycle touring adventures. Constructed from abrasion-resistant 420D TPU-laminated ripstop nylon with a 500D CORDURA® EVAC air-permeable base, it allows air to escape while keeping water out. The result is efficient compression without the need for a purge valve. Compact yet tough, the 8L version is ideal for insulating layers, clothing and compact sleeping gear.

Sea to Summit Evac Compression Dry Bag HD – 8L Key Features:

• Heavy-duty waterproof fabric: 420D TPU-laminated nylon body with 10,000mm hydrostatic head.
• EVAC air-permeable base: 500D CORDURA® base expels trapped air while blocking water.
• Secure roll-top closure: Hypalon non-wicking roll-top with Field Repair Buckle.
• Even compression system: Four straps prevent bulging and ensure tight packing.
• Strong lash loops: Reliable attachment to kayaks, bikes and racks.
• Reinforced seams: Double-stitched and tape-sealed for long-term durability.
• White interior laminate: Improves visibility when locating gear.

Specifications – 8L

• Best Use: Backpacking, Bikepacking & Motorcycle Touring
• Capacity: 8 Litres
• Weight: 220g
• Dimensions: 19.8 x 16.5 x 37.5 cm
• Closure: Hypalon roll-top with compression straps

Compact and extremely durable, the 8L HD is ideal for compressing smaller gear in exposed or high-abrasion environments.