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The pinnacle of Rab’s new sleeping bag range, built for efficient warmth with minimal weight
Rab says:
Every detail of the Mythic has been designed to reduce weight and bulk, drawing on over 40 years of hard-won expertise. It’s filled with high-quality 900FP down, which offers superb warmth for its weight, in our groundbreaking L.O.F.T 3D™ construction. This unique technology uses twisted, helix-shaped baffles to create funnel points within the bag, which prevent down from migrating and keep it evenly distributed. Combined with a TILT lining that reflects heat back towards your body, this allows us to achieve an unrivalled warmth-to-weight ratio. Light on grams but not on functionality, the Mythic is finished with a Pertex® Quantum ripstop fabric to ensure it stands up to mountain environments. Ultralight, stripped-back, and uncompromisingly warm, it’s ideal for moving fast in cold conditions, from fastpacking to alpinism.
Our Verdict
The Rab Mythic -12C / 10F is a highly focused ultralight sleeping bag that prioritises thermal efficiency and packability in colder conditions. At 906g, it remains impressively light for a winter-capable option, offering reliable warmth for sub-zero use in the UK. The TILT lining reflects radiant body heat towards you, helping retain warmth without adding bulk, while the L.O.F.T 3D baffle construction stabilises the down to reduce migration and maintain even insulation. Sidewall baffles slightly increase internal space and help maintain loft during movement, a benefit noticeable to side sleepers.
The half-length zip keeps weight down and still allows straightforward entry and exit, though it limits heat dumping from the legs in milder conditions. The cut is slim but well-shaped, with a secure hood and collar that hold warmth effectively.
- Reviewed by Ultralight Outdoor Gear
Features
- 10D Pertex® Quantum allows for greater loft and packability
- TILT lining helps to reflect and reduce heat loss
- Weight-saving L.O.F.T 3D™ baffle technology reduces down migration, optimising heat retention and reducing pack size
- Sidewall baffle construction for increased down loft and greater side sleeping comfort
- Anatomically fitted hood with drawcord adjustment to maximise comfort and heat retention
- Internal cordlocks positioned below the collar bone for greater side sleeping comfort
- 3D shaped down-filled neck collar
- 1/2 length YKK® 3 coil main zip with down-filled baffle to trap warmth
- Anatomically shaped foot box for relaxed sleeping posture
- Lightweight dry bag compression stuff sack
- Zipped storage sack with water-resistant base for home storage
- Hand-filled in Derbyshire UK
- Tapered mummy shape
- Temperature rated in accordance with ISO 23537-2:2022
Specifications
Temperature Rating
- Comfort: -5°C
- Comfort Limit: -12°C
- Extreme: -33°C
Regular
- Weight: 906g
- Lenth: 215cm
- Width: 80cm
Long
- Weight: N/A
- Lenth: 230cm
- Width: 80cm
Material & Construction
- 10D Pertex® Quantum ripstop (26g/m²) with fluorocarbon-free DWR
- 10D Recycled Atmos™ (28gsm) with Thermo Ionic Lining Technology (TILT)
- 900FP European goose down with Grangers fluorocarbon-free hydrophobic finish (590g / 20.8oz)
- 100% Woven Polyamide Shell , Down filled sleeping bag
