Ultralight down sleeping bag for hiking and three-season bivouacking
The Aegismax Leto sleeping bag is aimed at hikers and trekkers looking for a lightweight and compact 3-season sleeping bag, capable of covering a wide range of conditions without needing multiple pieces of equipment. The goal is clear: to set off with a single reliable bag for spring, summer, and early autumn, while keeping a lightweight and well-balanced backpack.
A sleeping bag designed for versatility on the move
The 700-fill power RDS-certified ultra-dry white goose down provides progressive and stable insulation, ideal for cool mid-season nights as well as summer bivouacs at altitude. In dry conditions and with a suitable insulated sleeping pad, it is equivalent to a 5-degree sleeping bag, with enough margin to handle nights around +2°C without major discomfort for an experienced user.
The mummy shape limits excess air volume to be heated and allows for the full benefit of the down, while maintaining enough freedom of movement for sleeping several nights in a row. The 3D footbox prevents the down from being compressed at the feet, a sensitive area when temperatures drop at the end of the season.
The 20D water-repellent ripstop nylon fabric effectively protects the down against dew, light humidity, and condensation encountered during three-season bivouacking. The two-way YKK zipper facilitates ventilation during milder nights. The Aegismax Leto is suitable for long-distance hiking, trekking, and lightweight bivouacking, for those who want a compact and lightweight sleeping bag that is versatile enough to last a full season without unnecessary compromises.
If you wish to gain an extra degree of thermal margin with an even thinner fabric (iFlex 7D) and a water-repellent treatment applied directly to the down, the Aegismax Dusk II is worth comparing.
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 Aegismax Leto has a comfort temperature of 7°C and a lower limit temperature of 2°C, measured to the EN 13537 standard. These values apply under standard conditions: sleeper in thermal base layers, on an insulated sleeping mat. It is designed for trek, bivouac use (3 seasons).
The Aegismax Leto is filled with 700 fill power ultra-dry white goose down, RDS certified. Down offers the best warmth-to-weight ratio: it packs down small and weighs less than synthetic insulation of equivalent warmth, which makes it the natural choice for wild camping and multi-day trekking. On the other hand, it loses efficiency when damp and needs careful drying. The Aegismax Leto weighs 642 g, which places it in the ultralight 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.