FREE UK DELIVERY £50+ | FREE UK RETURNS | EU & INT'L SHIPPING

FREE UK DELIVERY £50+ | FREE UK RETURNS

camp
  • By Activity
  • Runner in grey jacket and orange cap jogging on a dark forest path at dusk.

    Fastpacking & Running

  • Two hikers wearing headtorches and backpacks walking across rocky mountain terrain at dusk.

    Walking & Hiking

  • Tent pitched on moorland at sunset with mountains and lochs in the distance.

    Wild Camping

  • Group gathered around a campfire at night beside a glamping bubble tent strung with fairy lights, surrounded by birch trees.

    Vanlife

  • brands
  • journal
  • A hiker in a yellow and blue jacket takes a selfie on a mountain summit overlooking a lake and valley below.

    Best Outdoor YouTubers, TikTokers and Vloggers

  • Bright orange tent glowing from within at dusk in a snowy forest clearing.

    Forest Floor to Cosy Corner

  • Snow-capped mountains and moorland at Glencoe, Scotland, at sunset with a small lochan in the foreground.

    Mountain Base Camps | Glencoe, Scotland

  • Jørgen standing in a doorway wearing a dark blue shirt, with a home interior visible behind him.

    Interview: Jørgen Amundsen, Amundsen Sports

  • Lit candles in dark glass jars arranged on woven placemats with neutral textiles and dried botanicals.

    Nordic Nests

  • Ticket to the Moon hammock suspended between trees with mountain lake view below.

    Ticket To The Moon | The Story

  • Aerial view of a wild landscape with wetlands, blue waterways and rolling hills under a clear sky.

    Wild Places | 6 Amazing UK Rewilding Success Stories

  • Golden chanterelle mushroom growing in woodland moss and grass.

    Foraging Guide: Chanterelle Mushroom

  • bags-edc
  • home-garden
  • clothing
  • footwear
  • The go-to liner for three-season adventures

    If you're the sort who camps from spring through autumn rather than just August bank holiday weekend, the Reactor Midweight Liner is a great way to boost the warmth of your sleep system for those chillier shoulder-season nights. Thermolite Pro fabric and stretch-knit construction ensure cosy comfort, adding up to 6°C to your sleep system – which could be the difference between a comfortable night and lying there shivering until dawn. At 350g for the Regular, it's packable enough for backpacking trips, and the armholes with snap closures mean it doubles as a standalone sheet for hostel or hut stays. The technical hood and Free Flow compatible arm openings work with Sea to Summit bags, but it'll fit into any sleeping bag without bunching up. Machine washable, quick-drying, and treated with HeiQ Fresh so it doesn't start ponging after a fortnight on the trail.

      • Thermolite Pro hollow-core fibres add up to 6°C warmth
      • Stretch-knit fabric provides maximum comfort and freedom of movement
      • Technical hood and Free Flow compatible armholes
      • Armholes feature snap closures for versatile use
      • Easy to clean and extends sleeping bag lifespan
      • HeiQ Fresh odour control for extended use
      • Available in Short (170cm), Regular (185cm) and Long (198cm)
      • Snaps into Sea to Summit sleeping bags for easier entry
    • Size Max User Height Weight
      Short 170cm 320g
      Regular 185cm 350g
      Long 198cm 355g
      • Sustainability through Longevity - limited lifetime warranty guaranteeing freedom from material and manufacturing defects
    • What is it that attracts us to the idea of adventure? For Sea to Summit, it’s about freedom and self-reliance – the ability not just to survive, but to thrive in any environment. But although the brand takes its gear seriously, it does so with trademark Aussie humour and blunt, no bullsh*t candour. That’s the way it’s always been, ever since founder Roland Tyson made his first outdoor gear on an old industrial sewing machine in his childhood bedroom back in 1983, at the age of 17. Soon he was designing and manufacturing equipment for other Australian adventurers – and in 1991, he outfitted an unusual first ascent of Everest, in the form of a 1,126 kilometre journey from sea level to the mountain’s 8,848-metre summit. The name Sea to Summit was born.

      In 1993, Roland was joined by Penny Sanderson, another Aussie explorer and innovator. Their designs were honed on their adventures, as they spent months climbing, sailing, trekking, overlanding and biking. Nearly thirty years later, Sea to Summit is still 100% Aussie owned and operated, and still putting painstakingly designed gear into the hands of customers worldwide.

    Reactor Midweight Liner



    Size:
    Colour: Beluga
    Beluga
    Only 1 left
    Free UK Shipping On Orders £50+
    Free Returns For UK & EU Customers
    Price Match Guarantee
    No EU Customs Fees
    Platinum Trusted Service Award 2025

    The go-to liner for three-season adventures

    If you're the sort who camps from spring through autumn rather than just August bank holiday weekend, the Reactor Midweight Liner is a great way to boost the warmth of your sleep system for those chillier shoulder-season nights. Thermolite Pro fabric and stretch-knit construction ensure cosy comfort, adding up to 6°C to your sleep system – which could be the difference between a comfortable night and lying there shivering until dawn. At 350g for the Regular, it's packable enough for backpacking trips, and the armholes with snap closures mean it doubles as a standalone sheet for hostel or hut stays. The technical hood and Free Flow compatible arm openings work with Sea to Summit bags, but it'll fit into any sleeping bag without bunching up. Machine washable, quick-drying, and treated with HeiQ Fresh so it doesn't start ponging after a fortnight on the trail.

      • Thermolite Pro hollow-core fibres add up to 6°C warmth
      • Stretch-knit fabric provides maximum comfort and freedom of movement
      • Technical hood and Free Flow compatible armholes
      • Armholes feature snap closures for versatile use
      • Easy to clean and extends sleeping bag lifespan
      • HeiQ Fresh odour control for extended use
      • Available in Short (170cm), Regular (185cm) and Long (198cm)
      • Snaps into Sea to Summit sleeping bags for easier entry
    • Size Max User Height Weight
      Short 170cm 320g
      Regular 185cm 350g
      Long 198cm 355g
      • Sustainability through Longevity - limited lifetime warranty guaranteeing freedom from material and manufacturing defects
    • What is it that attracts us to the idea of adventure? For Sea to Summit, it’s about freedom and self-reliance – the ability not just to survive, but to thrive in any environment. But although the brand takes its gear seriously, it does so with trademark Aussie humour and blunt, no bullsh*t candour. That’s the way it’s always been, ever since founder Roland Tyson made his first outdoor gear on an old industrial sewing machine in his childhood bedroom back in 1983, at the age of 17. Soon he was designing and manufacturing equipment for other Australian adventurers – and in 1991, he outfitted an unusual first ascent of Everest, in the form of a 1,126 kilometre journey from sea level to the mountain’s 8,848-metre summit. The name Sea to Summit was born.

      In 1993, Roland was joined by Penny Sanderson, another Aussie explorer and innovator. Their designs were honed on their adventures, as they spent months climbing, sailing, trekking, overlanding and biking. Nearly thirty years later, Sea to Summit is still 100% Aussie owned and operated, and still putting painstakingly designed gear into the hands of customers worldwide.

    Sea to Summit

    Reactor Midweight Liner

    Size: Short
    Colour: Beluga + 0
    Colour Beluga
    Beluga