Montbell Sonic 0 Down Sleeping Bag

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A cold weather bag packed with high-quality down and technical features to keep you warm throughout the night.

Nemo says: 

Built to be the only bag you need from -20°F to 40°F, we’ve updated our Backpacker Editors’ Choice award-winning big-mountain bag, Sonic, for even greater warmth, tuneability, and reduced environmental impact. With this bag, we are launching our next-generation Thermo Gills™ with a new multistage zipper system that dramatically increases the usable temperature range of the bag and allows fine-tuning of comfort from within the bag. Sonic’s new chevron baffle construction better compartmentalizes down, eliminating migration and keeping the down evenly lofted. Not to mention, it looks awesome.

In updating the bag’s design, we put a high priority on taking a leap forward in sustainability. The shell and liner fabrics are 100% recycled fabrics and bluesign® approved. The premium 800 FP hydrophobic down is 100% Responsible Down Standard (RDS) certified. We also took years of history in the field to make detailed upgrades, including massaging the profile of the bag, redesigning the draft collar, and bolstering the draft tubes. Our proven Toester™ footbox keeps feet warmer, provides a waterproof barrier against tent wall condensation, and protects down from moisture while drying damp clothes inside the footbox. Adaptable to whatever the mountain throws at it, Sonic continues to reverberate as the ultimate extreme weather companion.

Our Verdict

The sonic 0 down utilises Nemo’sThermo Gills, shown by the two slits down the centre of the bag. They unzip to let warm air out if you get too hot at night, allowing you to vent body heat without letting cold drafts in, and they work well, especially in changeable conditions—the gills increase the bag’s versatility, expanding the comfort zone.

The bag has been “overstuffed” with an 800 FP down, which has been treated with a hydrophobic coating to help it shed water and dry quickly. They have also increased the bag’s water resistance with a waterproof foot box. I sleep in a small, single skin one-person tent, and without the waterproof foot box, I can often accidentally soak the foot end of my bag.

It’s a roomier fit than most traditional bags, which gives you more space to toss and turn; I was very impressed with the generous foot box size.

– Reviewed by Ultralight Outdoor Gear

Features

• Award-winning design is updated for even greater warmth retention and adjustability across temperatures. =Updated design incorporates 100% recycled, bluesign® approved shell and liner fabrics.
• Updated Thermo Gills™ extend the comfort range with a new multistage zipper system.
• Overstuffed with premium 800 FP hydrophobic down that is PFC-Free and 100% Responsible Down Standard (RDS) certified, ensuring humane treatment and traceability throughout the supply chain.
• New chevron baffle construction better compartmentalizes down for more uniform loft and down migration prevention. =Stretch construction at the knees for comfortable side sleeping.
• Redesigned draft collar and draft tubes keep cold air out.
• Redesigned Toester™ waterproof/breathable footbox utilizes a layer of synthetic insulation to protect the down and deliver maximum toastiness for toes.
• Offset zipper creates a thermally efficient seal while an updated profile secures warmth closer to the body.
• Protected by the NEMO Lifetime Warranty.

Specifications

Temperature Rating (EN 13537)

• Comfort: -10°C / 14°F
• Comfort Limit: -18°C /0°F
• Extreme: -36°C / -33°F

Regular

• Weight: 1544g (excluding stuff sacks)
• Fill weight: 790g
• Fits up to: 6′ / 183 cm
• Shoulder girth: 63 in / 160 cm
• Hip girth: 58 in / 147 cm
• Knee girth: 53 in / 135 cm
• Packed size: 13.5 x 9.5 in / 34 x 24 cm

Long

• Weight: N/A (excluding stuff sacks)
• Fill weight: 835g Fits up to: 6’6″ / 198 cm
• Shoulder girth: 65 in / 165 cm
• Hip girth: 60 in / 153 cm
• Knee girth: 55 in / 140 cm
• Packed size: 14 x 9.5 in / 36 x 24 cm

Material & Construction

• Temperature Ratings Temp rating: 0F / -18°C
• ISO lower limit: 14F / -10°C

Help & advice:

• The Ultimate Guide to Lightweight Sleeping Bags
• Time-Saver Guide to Choosing a Sleeping Bag
• The EN13537 Standard
• Sleeping Bag Shapes & Sizes
• Sleeping Bag Features 1
• Sleeping Bag Features 2
• Choosing a Sleeping Mat
• About Nemo
• Nemo Sleeping Bag Guide
• Nemo Video Resources