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What is the Big Agnes Greystone 30° Long Left Sleeping Bag?
The Greystone 30° is a versatile all-gender mummy sleeping bag designed for backpackers, travellers, and anyone seeking dependable warmth without extra weight. It combines high thermal efficiency with compressibility, making it easy to pack into your kit whether on a backcountry mission, camping with friends, or crashing indoors during a trip. Its contoured hood, draft-blocking design, and water-resistant materials ensure you'll sleep comfortably in various conditions.
What is it made of?
Insulation
At the heart of the Greystone 30° is 600-fill DownTek down insulation, which delivers a balance of warmth and packability. Down is prized in outdoor gear for its ability to trap body heat while remaining exceptionally lightweight and compressible. Fill power measures the loft and insulating efficiency of the down—the higher the number, the greater the warmth-to-weight ratio. At 600 fill power, the Greystone offers reliable thermal performance for three-season conditions without adding unnecessary bulk to your pack.
What sets DownTek™ apart from untreated down is its bluesign®-approved, PFAS-free water-repellent treatment. Traditional down loses loft and insulating power when exposed to moisture, collapsing into clumps that trap little heat. DownTek™, however, resists water absorption, allowing it to maintain loft up to 90% longer in damp or humid conditions. It also dries significantly faster, so it will remain warm and functional even if your bag is exposed to condensation, morning dew, or the occasional spill. This technology bridges the gap between natural down's superior warmth-to-weight and the moisture resistance often associated with synthetic insulation, ensuring reliable comfort in backcountry conditions.
Shell
The outer fabric of the Greystone 30° is made from recycled polyester ripstop, chosen for its excellent strength-to-weight ratio and long-term durability. The "ripstop" weave pattern integrates stronger reinforcement threads into the fabric, preventing holes or tears from forming and spreading. This weave makes it more resistant to abrasion and wear from rough ground, frequent packing, or contact with outdoor gear. On top of this, the shell is finished with a PFAS-free Durable Water Repellent (DWR) coating. Unlike traditional DWR finishes that often rely on harmful fluorochemicals, this alternative effectively sheds light moisture inside a tent, such as condensation or drips, while reducing environmental impact.
Lining
Inside, a recycled polyester taffeta lining provides a soft, smooth feel against the skin, enhancing comfort for nights when you're not layering up heavily. This lining also benefits from a PFAS-free water-repellent treatment, a second barrier to protect the down insulation from moisture that might penetrate the outer shell.
Construction
The Greystone 30° uses a baffled construction, a design where the down insulation is contained within stitched chambers. Unlike simpler "sewn-through" designs that can create thin, cold-prone spots, baffled construction allows the down to fully loft within evenly spaced compartments.
Additionally, baffled construction enhances the long-term durability of the bag's insulation. It preserves loft even after years of compression and expansion cycles by preventing the down from shifting or clumping into corners.
What are its features?
Thermal Efficiency
The mummy shape reduces bulk and weight while increasing body heat retention. A contoured hood follows the natural shape of your head, while an oversized no-draft collar, no-draft zipper, and insulated tube along the hood opening seal in warmth.
User-Friendly Design
A low-profile cordlock allows you to uncinch the hood with one hand. The smooth-running 165 cm YKK #5 two-way anti-snag zipper is positioned on the left side, complete with a zipper garage for snag-free operation.
Adaptability
Left-zip all-gender Greystone bags can be mated with right-zip women's models to create a shared sleep system. Interior loops let you attach a liner for extra warmth (sold separately), while exterior loops allow for hang drying or long-term storage.
Packability and Versatility
The Greystone 30° compresses into a compact 19 × 20 cm size for backcountry use. To preserve loft for long-term storage, a 14L sack (20 × 45 cm) is included. It's compatible with any Big Agnes sleeping pad, though we recommend higher-insulation pads in colder conditions.
Comfort and Temperature Ratings
Independently tested to ISO 23537-1 standards, the Greystone 30° offers reliable temperature guidance:
- Comfort: 3°C (37°F) — the lowest temperature at which the average woman will sleep comfortably.
- Lower Limit: -3°C (27°F) — the lowest temperature at which the average man will sleep comfortably.
- Extreme: -19°C (-2°F) — survival rating for an average woman.
Features:
- Lightweight mummy-style design for warmth and efficiency
- 600-fill DownTek PFAS-free, water-repellent down
- Recycled polyester ripstop shell with PFAS-free DWR finish
- Recycled polyester taffeta lining with PFAS-free DWR finish
- Contoured hood with low-profile cordlock for one-hand adjustment
- Oversized no-draft collar, draft tube, and zipper garage for thermal protection
- YKK #5 two-way anti-snag zipper on left side
- Liner loops and exterior storage loops for adaptability
- Mateable design (left + right zip bags) for two-person use
- Stuff sack and storage sack included