Rab Mythic Ultra -12°C Sleeping Bag | Ultralight High Mountain Down Sleeping Bag

Description

The Rab Mythic Ultra -12°C / 10F is an ultralight down sleeping bag designed for those who need maximum thermal efficiency with the lowest possible weight. It is clearly a piece oriented towards fast & light, mountaineering, technical traverses, and winter mountain environments where every gram counts, without sacrificing a serious level of protection.

Its combination of 900FP European goose down, L.O.F.T 3D™ construction, and a liner with TILT technology places this model at the premium end of Rab's range. The result is an extraordinarily lightweight, highly compressible bag with a warmth-to-weight ratio that is difficult to match in the technical segment.

Real Technical Performance

The Mythic Ultra -12°C is not intended for general camping or casual use, but for users who prioritize pure performance, lightness, and compressibility. The L.O.F.T 3D™ construction uses helical baffles that help minimize down migration and maintain uniform insulation distribution, improving thermal consistency in real-world use.

The TILT technology, integrated into the liner, helps reflect body heat and reduce radiant heat loss without adding unnecessary bulk. This allows the 590g of 900FP down to be used to its maximum potential, creating a very serious bag for cold conditions with a total weight of only 920g. Compared to a more robust bag like the Neutrino, the focus here is clearly on minimal weight, minimal volume, and maximum efficiency.

Quantitative Technical Specifications

• Total Weight: 920 g / 2 lb 0.45 oz
• Fill: 900FP European goose down with fluorocarbon-free hydrophobic finish (590 g / 20.8 oz)
• Outer Fabric: 10D Pertex® Quantum ripstop (26 gsm) with fluorocarbon-free DWR
• Liner: 10D Recycled Atmos™ (28 gsm) with Thermo Ionic Lining Technology (TILT)
• Comfort Temperature: -5°C / 23°F
• Limit Temperature: -12°C / 10°F
• Extreme Temperature: -33°C / -27°F
• Packed Size: 20 cm x 35 cm (7.9 in x 13.8 in)
• Shape: tapered mummy
• Product Code: QSN-26

Comparison within the Range

Within the Mythic Ultra family, this model sits above the Mythic Ultra 0°C and the Mythic Ultra -6°C in thermal protection, targeting colder conditions and more demanding technical activities. Compared to those models, it increases the safety margin in winter mountaineering in exchange for a little more weight and volume.

Compared to the Neutrino family, the Mythic Ultra plays a different game: less overall robustness and less room for casual use, but a much more focused proposition on premium ultralightness. This is the bag for those who value extreme compressibility and the maximum warmth-to-weight ratio above all else.

Recommended Use

• Light mountaineering and fast ascents in cold conditions
• Technical fastpacking and traverses where every gram matters
• Ultralight winter mountaineering
• Experienced users who prioritize weight, packability, and performance

Is it for you?

Yes, if you are looking for one of Rab's most efficient down sleeping bags in terms of warmth-to-weight ratio. Yes, if you engage in alpine activities, fast & light, or winter mountaineering and need to minimize backpack volume. No, if you prefer a more robust bag, more tolerant to intensive use, or with a less radical approach; in that case, a Neutrino might be a better fit.