Optimized natural insulation for summer bivouacking
The Aegismax Leto demonstrates the full superiority of a down sleeping bag when it comes to combining thermal efficiency with absolute lightness. Unlike synthetic fibers, down provides progressive and highly breathable warmth, avoiding the suffocating feeling typical of summer nights in a tent. This model includes just enough fill to keep you secure during cool nights at medium altitude, without weighing you down unnecessarily during the day.
Down stability and anti-condensation protection
The RDS-certified 700-fill goose down features an ultra-dry treatment, a vital technology to prevent the feathers from clumping when in contact with moisture in the tent. The mummy fit, combined with a 3D footbox, allows the insulating material to fully loft without being compressed by your feet. The 20D ripstop nylon ensures the longevity of this lightweight sleeping bag against the rigors of the trail.
290g fill and anti-snag zipper
The insulation consists of 290 g of 700-fill-power RDS-certified white duck down, bringing the total weight of this trekking sleeping bag to 525 g. This ratio makes it possible to evaluate the actual density of the insulation independently of the stated weight. The zipper features an anti-snag system that prevents the fabric from being pinched when opening or closing, a common point of wear on ultralight bags with thin shells.
38g compression sack included
The included compression sack weighs 38 g and allows this ultralight sleeping bag to be reduced to a 12 x 21 cm package. This weight figure for the accessory itself is useful for those who calculate the total load of their sleeping gear precisely, accessories included.
If you are looking to cover a wider temperature range with a safety margin around the freezing point (0°C) for extended use until late autumn, the superior insulation volume of the Black Snow 3-Season will better meet this need for versatility.
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 hiking, trekking use (3 seasons).
The Aegismax Leto is filled with 700 fill power, RDS certified. The Aegismax Leto weighs 604 g, which places it in the ultralight category.
A down sleeping bag is insulated with goose or duck down and feathers, whereas a synthetic bag uses polyester fibres. Down offers a better warmth-to-weight ratio and packs smaller than synthetic insulation of equivalent warmth; synthetic keeps more of its insulation when damp.
A well-maintained down sleeping bag retains 80 to 90% of its insulating properties after 5 to 10 years of regular use. The main cause of degradation is long-term compressed storage, which gradually breaks the down clusters. Washing once a year with a down-specific detergent and storing the bag uncompressed out of season significantly extend the life of the fill.
The ideal comfort rating depends on intended use. For summer trekking in France (Alps, Pyrenees, GR20), a comfort temperature between 0°C and +3°C covers almost all situations. For static summer camping in the lowlands, +5°C to +10°C is enough. For extreme cold or winter wild camping in the mountains, aim for -10°C comfort minimum. The comfort temperature is always measured to EN 13537 / ISO 23537-1 / GB/T 38426.