Rab Mythic 400 Down Sleeping Bag (-6°C/20°F)

The Mythic collection is crafted with a singular purpose—stripping away weight wherever possible. The Mythic 400 stands out as an ultra-lightweight sleeping bag built for three-season use. Perfectly suited to life in high-altitude environments, it thrives on extended Alpine missions, multi-day climbs, adventurous treks, and minimalist bikepacking excursions.

Tipping the scales at only 700g, it’s filled with 400g of premium 900FP goose down. The distinctive chevron-shaped baffle layout holds the down securely in place, enhancing warmth at the core while using less fabric than standard horizontal baffles. Its outer shell is made from Rab’s own Atmos™ fabric, a recycled material offering both wind and water resistance. Shaped with a slimline mummy profile to reduce excess bulk, it also features lightweight zips and pullers, and comes with a waterproof roll-top compression sack that ensures protection against the elements while keeping pack size to a minimum.

The innovative trapezoid boxwall baffle construction allows the down to loft fully, eliminating cold spots and boosting thermal efficiency. Additional warmth is preserved with an adjustable neck baffle and a full-length internal zip baffle, both designed to prevent valuable heat from escaping. Each bag is hand-filled in the UK, ensuring that the down remains uncompacted prior to use, preserving its natural loft and insulating power.

Features

• The chevron baffle construction reduces down migration while enhancing warmth in the core.
• A trapezoidal boxwall build with differential cut ensures maximum loft and thermal retention.
• A close-fitting, adjustable neck baffle is included to minimise heat loss around the upper body.
• The YKK® three-quarter length main zip is backed with a synthetic-filled baffle to help trap warmth.
• A YKK® internal zipped stash pocket offers a handy space for storing small essentials.
• An angled foot box design allows for a natural and relaxed sleeping position.
• A bonded anti-snag zip guard helps prevent fabric from catching in the zip.
• Comes complete with a lightweight, waterproof, roll-top compression sack for compact packing and protection from the elements.
  
  

Sustainability Features

• Fluorocarbon (PFAS) free fabric
• Fluorocarbon (PFAS) free product
• Made with renewable energy
  
  

Specifications

Size Guide

Technology

Atmos™

Designed for mountain adventures, Atmos™ offers exceptional weather protection while remaining packable and quick-drying. Crafted with ultra-fine yarns in a tightly woven construction, it delivers impressive durability, high water resistance, and reliable windproof performance.

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