Expedition sleeping system for extreme environments
The Aegismax G5 extreme cold sleeping bag is a critical piece of equipment intended for mountaineers and experienced winter bivouackers. When the thermometer drops below -20°C, there is no room for error. This model utilizes an exceptional density of natural down to create an impenetrable insulating barrier, capable of maintaining your body temperature at a safe level throughout the night.
Thermal engineering and thermal bridge mitigation
Performance at these temperatures relies on a strict architecture: box-baffle construction that prevents the 800-fill power RDS-certified down from migrating to the extremities. The anatomical footbox and the ultra-covering insulated hood lock in areas of high heat loss. The 15D iFlex® nylon shell, treated with a water-repellent finish, effectively protects the down from internal tent frost, ensuring constant loft during prolonged exposure to freezing conditions.
Full-baffle structure against cold spots
Beyond the box-baffle construction already described, the build relies on continuous transverse baffles that distribute the RDS-certified goose down across the entire width of the bag. This continuity in the baffling limits the migration of down to one side when moving during sleep in this extreme cold sleeping bag.
Technical components: YKK zip and Duraflex buckles
The zipper uses a YKK 5 Nylon zip and the adjustment buckles are Duraflex, two components recognized in outdoor equipment for their durability. The snag-free PAIHO velcro protects the outer fabric from gradual damage during repeated handling of this extreme cold sleeping bag.
Finally, if your expeditions involve committed mountaineering at -30°C and extreme gear weight reduction is a matter of safety, the ultralight engineering of the Aegismax Ultra model will allow you to get below the 1.6 kg mark for absolute warmth.
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 G5 has a comfort temperature of -23°C and a lower limit temperature of -30°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 Mountaineering, expedition use (4 seasons / Extreme cold).
The Aegismax G5 is filled with 800 fill power, RDS certified. The Aegismax G5 weighs 1768 g, which places it in the standard category.
Yes, provided they are used within their real temperature range. A cold-weather bag is designed to keep the sleeper warm below -10°C, but its effectiveness also depends on the insulated sleeping mat (R-value 4 minimum), the clothes worn at night and ambient humidity. The bag alone does not guarantee comfort: it is the complete sleep system that counts.
Several factors determine real thermal comfort: using a sleeping mat with a suitable R-value (R4 minimum for extreme cold), wearing thermal base layers and dry socks, eating enough before sleeping to fuel body-heat production, and making sure the bag is completely dry. A damp bag loses a significant part of its insulating properties, especially down.
The lower limit temperature is the lowest temperature at which a reference man can maintain his body heat curled up, according to EN 13537 / ISO 23537-1. It usually sits a few degrees below the comfort temperature, and the gap varies between models: check the figure on each product page. Below this threshold, comfort is no longer assured — the comfort temperature remains the main selection criterion.