The mummy cut really does keep heat locked in where you need it most on winter trips.









Cold-Weather Down Sleeping Bag for Winter Camping & Backpacking – Lightweight Insulated Mummy Bag Rated to -4°F for Hiking, Trekking & | Thomler
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Sleep Warm When the Temperature Drops
This premium down sleeping bag delivers serious cold-weather protection without the weight penalty. Stuffed with 90% duck down insulation, it traps body heat efficiently while staying ultralight and compressible in your pack. The ripstop nylon shell repels moisture and resists tears, and the fitted hood and insulated footbox seal out drafts. Whether you're winter camping in the backcountry or trekking through alpine zones, you get reliable warmth in a packable design. The tapered mummy cut maximizes heat retention, and dual zippers let you vent or connect two bags for shared comfort. Built for serious cold, this bag keeps you cozy when conditions turn harsh, so you can focus on the adventure instead of shivering through the night.

Why You Need This
- Rated to -4°F: High-loft down insulation keeps you warm in sub-zero conditions, so you sleep soundly even on the coldest nights.
- Packable & Light: Despite its warmth, the bag compresses small and weighs far less than synthetic alternatives—less burden on long treks.
- Durable Shell Fabric: Ripstop nylon resists punctures and sheds light rain, protecting your investment trip after trip.
- Draft-Blocking Design: Adjustable hood and insulated footbox prevent heat loss at your head and feet, the zones that chill fastest.
- Connectable: Zip two bags together to create a double-wide system, perfect for couples or extra room to move.
- Multiple Weight Options: Choose your fill weight to match your trip—lighter for mild cold, heavier for extreme expeditions.
Built for the Backcountry
Every detail—from the snag-free zippers to the compression stuff sack—is designed to perform in real outdoor conditions. The down fill meets rigorous quality standards, ensuring loft recovery and long-term reliability. Available in several colors to suit your style, and offered in fill weights from 14 oz to 42 oz, so you can dial in the exact warmth-to-weight ratio you need. Whether you're a weekend warrior or a serious mountaineer, this bag adapts to your plans. And with free shipping across the US and a 30-day return window, you can test it risk-free before your next trip into the cold.
Free shipping across the United States — always, with no minimum order.
Every order is carefully packed and sent with Track & Trace, so you can follow your package every step of the way.
Order today? We ship the next business day.
Not completely happy? You have 30 days to return your purchase.
On top of that, we offer a 3-year warranty against manufacturing defects — your investment is in good hands.
Made for everyday
Practical pieces you’ll actually use.
Quality first
Chosen for quality you can feel.
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What Our Customers Say
Discover what makes THOMLER special.
Compresses down so small it barely takes up room in my backpack alongside other gear.
Hood cinches tight enough to stop cold air from sneaking in around your face and neck.
Took this on a three-day trek through the mountains in February and stayed comfortable the whole time. The footbox design keeps your toes from going numb, which makes a real difference when you're sleeping at elevation.
I like that you can connect two bags together if you're camping with someone. Makes the whole sleep system more flexible depending on who's going on the trip and what the conditions are like.
The ripstop shell has held up through multiple seasons of rough handling—getting stuffed into stuff sacks, dragged across rocky ground, and still no tears or punctures showing up anywhere on mine.
As seen in
Yours, the moment we pack it
- Hand-packed with care
- Checked before it ships
- Arrives exactly as pictured
Straight From Your Camera Roll
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A note from our team
Shopping for your home shouldn't feel like a gamble.
Too many products look great online and disappoint when they arrive. That's why we only pick pieces we'd happily put in our own homes.
Not right for you? Send it back within 30 days, no hassle. And when you email us, a real person from our small team answers.
The Thomler Team
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