The Sea to Summit Spark -1C/30F Down Sleeping Bag - Regular invites adventurers to experience unparalleled comfort and warmth on their journeys. This meticulously crafted sleeping bag features RDS-certified, 850+ fillpower goose down, treated with a non-PFC Ultra-Dry Down to ensure optimal insulation even in damp conditions. Its ultralight design makes it a breeze to carry, while the breathable 10D nylon liner and shell, both treated with PFC-free DWR, guarantee a cosy and dry night's sleep. The technical hood, anatomical footbox, and ergonomic mummy shape provide tailored comfort, ensuring a restful sleep, while the reliable YKK #5 zippers offer durability and ease of use, making it a perfect companion for any adventure.

Sea to Summit Spark -1C/30F Down Sleeping Bag - Regular Features:

• RDS-certified, 850+ fillpower goose down with a non-PFC Ultra-Dry Down treatment: Delivers superior warmth-to-weight ratio and maintains insulation in damp conditions.
• Ultralight: Ideal for backpacking and minimalist adventures, ensuring minimal weight without compromising on comfort.
• Breathable 10D nylon liner and a 10D shell with PFC-free DWR: Provides excellent ventilation and water resistance, keeping you dry and comfortable.
• Technical hood, anatomical footbox and an ergonomic mummy shape: Designed to enhance fit and comfort, offering a snug and natural sleeping position.
• YKK #5 zippers: Robust and smooth-operating zippers ensure easy access and long-lasting performance.

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

Built for fast-and-light adventures without sacrificing real warmth, the Sea to Summit Spark Down Sleeping Bag -1C|30F – Long (RDS) is a premium 2-season ultralight bag designed for serious backpackers counting grams. It’s filled with RDS-certified 850+ fillpower goose down treated with a non-PFAS Ultra-Dry Down treatment for reliable thermal performance in damp conditions. A super-breathable 10D liner and 10D shell with PFAS-free DWR keep things comfortable and help shed wind and condensation, while the highly water-repellent hood and footbox fabric add extra protection where it matters most. The technical hood and zipper draft tube help seal in warmth, and the ergonomic mummy shape keeps the fit efficient without feeling overly restrictive. For couples, the full-length zipper models in the Spark range can be zipped to an equivalent Women’s Spark for shared comfort.

Sea to Summit Spark -1C Long – Key Features

• RDS-certified 850+ down: Goose down with non-PFAS Ultra-Dry Down treatment for high warmth-to-weight performance.
• Ultralight 10D fabrics: Breathable 10D liner and a 10D shell with PFAS-free DWR for comfort and weather resistance.
• Technical warmth features: Technical hood and zipper draft tube to retain heat on cooler nights.
• Ergonomic mummy shape: Efficient thermal fit without being “ultra tight”.
• Snag-free zipper performance: YKK #5 zipper with zipper plough for reliable, smooth operation.
• Temperature-specific construction: Hybrid baffle design (box baffles in torso, sewn-through in leg area) to balance warmth and weight.
• Lifetime backed: Sea to Summit Guarantee is offered for the lifetime of the product.

Specifications – Spark Down Sleeping Bag -1C|30F (Long)

• Best Use: Ultralight Backpacking
• Performance: 2 Season
• Temperature Rating (ISO Lower Limit): -1°C
• Women's Temp Rating (ISO Comfort): 4°C
• Insulation: RDS certified, 850+ non-PFAS Ultra-Dry Down
• Shape: Mummy
• Zip Options: YKK #5 zipper with snag free zipper plough
• Weight: 536 g
• Fill Weight: 305 g
• Compressed Volume: 5.1 L
• Compression Sack: 8 L (40D recycled, bluesign APPROVED nylon compression bag)
• Fits Up To Height: 198 cm

Sea to Summit Spark Down Sleeping Bag -9°C | 15°F – Long – Ultralight, high-performance warmth for serious weight-conscious adventurers.

Sea to Summit Spark Down Sleeping Bag Key Features:

• Premium Insulation: Filled with RDS-certified 850+ fill power goose down treated with non-PFC Ultra-Dry Down for exceptional warmth in damp conditions.
• Ultralight Construction: 10D nylon shell and liner with PFC-free DWR, plus a water-resistant hood and footbox for added weather protection.
• Ergonomic Design: Technical hood, anatomical footbox, and an ergonomic mummy shape balance warmth with comfort and freedom of movement.
• Advanced Baffle System: Full box baffles retain heat in extreme cold, supported by YKK #5 snag-free zippers and draft tubes to trap warmth.

Weighing just 786g and compressing to 7.6L, the Spark -9°C Long is built for performance without compromise—perfect for alpine missions, cold-weather trekking, or lightweight expeditions up to 198cm in height.

Experience the ultimate in camping comfort with the Sea to Summit Reactor Sleeping Bag Liner - Compact Mummy w/ Drawcord. This liner is designed to add warmth to your sleep system in cool or cold conditions, making it an essential addition to your camping gear. The Reactor liner uses Thermolite® Pro fabric with infra red-absorbing ceramic pigments and Thermolite® EcoMade fibres to take thermal performance to the next level. It's not just about warmth though, the stretch-knit fabric provides optimal comfort and ensures the Reactor fits any sleeping bag. The classic Mummy version even has practical shoulder openings for those who like to stretch out. The Mummy with Drawcord version offers the versatility of walking around camp while still wearing your liner, thanks to its footbox opening. Plus, with HeiQ Fresh odour control technology, your liner will stay fresh even after extended use. And for peace of mind, the Sea to Summit Guarantee is offered for the lifetime of this product.

Sea to Summit Reactor 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 in colder conditions.
• Thermolite® Pro Technology: The liner uses knitted, hollow-core fibres and infrared-absorbing ceramic pigments to reflect your body's heat back for enhanced warmth and comfort.
• Classic Mummy Version: This version has practical openings in the shoulders to allow the user to stretch his or her arms out.
• Drawcord Footbox Version: In this version, the base or shoulder openings can be opened or closed for optimal comfort. They integrate perfectly with the Free-Flow Zip system in select Sea to Summit sleeping bags. Open the base drawcord, and you can hitch the liner up and walk around camp - perfect for bathroom breaks.
• HeiQ Fresh Odour Control Technology: This technology helps keep the liner fresh even after extended use.
• Knitted Fabric: The fabric provides incredible stretch and freedom of movement - Reactor liners work perfectly with sleeping bags of any shape.
• Sea to Summit Guarantee: A guarantee is offered for the lifetime of this product.