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 a piece clearly oriented toward fast & light, mountaineering, technical traverses, and winter alpine use 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 lining with TILT technology places this model at the premium end of the Rab range. The result is an extraordinarily light, highly compressible sleeping bag with a warmth-to-weight ratio that is hard to beat within 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 a uniform distribution of insulation, which improves thermal consistency in real-world use.

The TILT technology, integrated into the lining, helps reflect body heat and reduce radiant heat loss without adding unnecessary bulk. This allows for maximizing the 590g of 900FP down, resulting in 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 minimum weight, minimum 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 g/m²) with fluorocarbon-free DWR
• Lining: 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, being oriented toward cold conditions and more demanding technical activity. Compared to those models, it increases the safety margin in winter mountains at the expense of a little more weight and volume.

Compared to the Neutrino family, the Mythic Ultra plays a different game: less overall robustness and less margin for casual use, but a much more focused approach on premium ultralightness. It is the bag for someone who values extreme compressibility and 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
• Winter mountains with an ultralight focus
• 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 activity, fast & light, or winter mountaineering and need to reduce your pack volume as much as possible. No, if you prefer a more robust bag, more tolerant of intensive use, or with a less radical approach; in that case, a Neutrino may be a better fit.