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A warm, reliable synthetic sleeping bag designed for dependable cold-weather use.
Big Agnes says:
The Anthracite traditional mummy style sleeping bag is designed to provide superior rest after a long day spent outside. Stay cozy with Fireline™ Pro Eco recycled synthetic insulation and stay dry with a durable moisture repellent coating. Lightweight enough to stuff in your pack for summer backpacking but comfortable enough for backyard campouts with the kids, this bag is so versatile and comfortable you’ll want to take it on every outing!
Our Verdict
The Anthracite 20 uses Fireline Pro Eco synthetic insulation to deliver consistent warmth and weighs 1221g. Synthetic insulation is less compressible than down, but handles moisture far better and is much easier to wash and dry, making it a practical choice for damp UK conditions. The comfort limit of around -8°C provides enough range for colder shoulder-season use, allowing comfortable use from early spring through to late autumn, pushing comfortably into sub-zero temperatures, when paired with an appropriate mat.
The mummy cut is shaped for efficiency but remains more forgiving than many performance-focused designs, allowing comfortable movement in the bag without sacrificing too much heat retention. A full-length zip offers good ventilation control, making it easier to manage temperature in camp as conditions change. The hood and draft collar seal well, helping retain warmth on colder nights.
The recycled fabrics feel durable without being overly heavy, and the overall construction is straightforward and functional. The pack size is larger than that of a comparable down bag, reflecting the synthetic insulation, but the trade-off is more reliable performance in damp environments.
Overall, this is a well-balanced option for those prioritising comfort, ease of use and consistent warmth in a dependable three-season sleep system.
- Reviewed by Ultralight Outdoor Gear
Features
- Delivers technical, lightweight performance with high thermal value, compressibility
- FireLine™ Pro Eco synthetic insulation provides reliable, efficient warmth in any situation
- Traditional mummy shape allows for light weight and increased body heat retention
- Contoured hood follows the shape of your head for a more comfortable fit
- Oversized no-draft collar and no-draft zipper to keep the cold out
- Mate together left (All-Gender) and right (Women’s) zip bags to share warmth with your tent mate
Specifications
Regular -
- Weighs: 1221g
- Fits: fits up to 183cm
- Stuff Sack Size: 23 x 51cm
- Comfort Temperature: 29°F / -2°C
- Limit Temperature: 18°F / -8°C
- Extreme Temperature: -15°F / -26°C
Long -
- Weighs: 1370g
- Fits: fits up to 198cm
- Stuff Sack Size: 23 x 51cm
- Comfort Temperature: 32°F / 0°C
- Limit Temperature: 22°F / -6°C
- Extreme Temperature: -9°F / -23°C
Wide Long -
- Weighs: 1602g
- Fits: fits up to 198cm
- Stuff Sack Size: 23 x 51cm
- Comfort Temperature: 32°F / 0°C
- Limit Temperature: 22°F / -6°C
- Extreme Temperature: -9°F / -23°C
Material & Construction
- Shell: Recycled polyester ripstop with water-repellent finish without intentionally added PFAS
- Lining: Recycled polyester taffeta with water-repellent finish without intentionally added PFAS
- Fill: Fireline™ Pro Eco
