Lightweight sleeping bag for hiking and mid-mountain trekking
The Naturehike SP400 5-degree sleeping bag is structured for hikers looking for the exact balance between reassuring warmth and lightness. By incorporating 400 grams of natural filling while staying under the one-kilo mark, this model guarantees restful sleep during spring and autumn bivouacs, where strictly summer equipment would show its limits in the early morning.
Safe thermal design and certified down
The presence of a windproof thermal collar and a 3D footbox (expanded space for the feet) demonstrates a serious design aimed at blocking cold air infiltration. The filling uses RDS-certified 650 cuin down, ensuring traceability and lasting thermal resilience. This hiking sleeping bag is a versatile ally.
RDS-certified down: traceability of the filling
The 650 cuin duck down is RDS (Responsible Down Standard) certified, which documents the origin and treatment of the down used in this mid-season winter duvet. This traceability complements the fill power data already mentioned, without replacing it.
20D water-repellent nylon fabric: protects down from light moisture
The 20D nylon outer fabric incorporates a water-repellent treatment that protects the down filling from light moisture (dew, tent condensation), an important point for this cold-weather sleeping bag since natural down loses some of its insulating power once wet.
Nevertheless, for trekkers committed to purely summer routes where every gram counts, an ultra-compact option without a hood like the Aegismax Nano will help save even more packing volume.
Why pay more for the same performance?
The Naturehike SP400 was compared with the Decathlon Forclaz MT900. The finding is simple: you get equivalent technical features and warmth without paying the brand premium. Keep your budget for your next expedition.
Data checked against the brands' official product pages — subject to change.
Doubt about which bag is right for you?
The field guide helps you choose based on skill level, temperature, needs, and weight. Support answers specific questions.
Find my bag Contact supportFrequently Asked Questions
The Naturehike SP400 has a comfort temperature of 3.8°C and a lower limit temperature of -1.4°C, measured to the ISO 23537 / GB/T 38426-2019 standard. These values apply under standard conditions: sleeper in thermal base layers, on an insulated sleeping mat. It is designed for hiking, bivouac, trek use (3 seasons).
The Naturehike SP400 is filled with 650 cuin. The Naturehike SP400 weighs 820 g, which places it in the lightweight category.
A 3-season sleeping bag is designed for spring, summer and autumn. Its comfort temperature sits between 0°C and +5°C, which covers most wild camps in France up to 2,500 m outside winter conditions. In winter or above 2,500 m, a dedicated cold-weather bag is needed.
A 3-season bag is suited to night-time temperatures between roughly 0°C and +15°C. Below 0°C, thermal comfort is no longer assured without extra equipment (liner, additional sleepwear). Above +15°C, most sleepers will find the bag too warm: venting through the foot zip helps regulate.
For the vast majority of walkers and trekkers in France (GR20, GR5, Tour du Mont Blanc from June to September), a 3-season bag with a 0°C comfort rating is sufficient. A 4-season bag is only needed above 3,000 m outside summer, in winter conditions, or for exposed high-altitude wild camps in autumn.