Therm-A-Rest Boost 20F / -6C Down Sleeping Bag
COMFORT ISN’T ‘ONE SIZE FITS ALL’, SO THE THERM-A-REST BOOST 650 ALLOWS YOU TO CUSTOMISE ITS SHAPE FOR THE PERFECT BALANCE OF SPACE AND WARMTH.
The Boost Sleeping Bag is designed for maximum comfort, featuring a spacious semi-rectangular shape that offers ample room for side sleeping, shifting positions, or stretching out without feeling restricted. Unlike a traditional mummy bag, the semi-rectangular design provides significantly more internal space, allowing you to sleep in any position, whether curled up or fully stretched. You'll enjoy the freedom to relax however you prefer throughout the night.
While the extra space provides comfort, it also means you need more warmth to stay cosy, and that’s where the innovative WarmZip comes into play. This clever feature ensures you stay warm even in cooler conditions, keeping you comfortable through the night.
Explore our full range of Down Sleeping Bags here.
KEY FEATURES OF THE BOOST 650
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Customisable Comfort: Choose between a semi-rectangular bag or mummy bag for tailored warmth and space.
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WarmZip™ Tech: Patent-pending centre zipper design reduces internal space, boosting warmth by up to 10°F/6°C.
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Multi-Use Arm Holes: Reach the WarmZip, read, play cards, or ventilate, all while staying inside your bag.
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Plush & Puffy: 650-fill RDS-certified hydrophobic down with Zoned Insulation for enhanced heat efficiency and comfort.
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Eco-Conscious Materials: Shell and liner made from 100% recycled nylon with PFAS-free water repellent coating.
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Inclusive Sizing: Available in Short, Regular, Long, and Wide for a customised fit.
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Additional Features: YKK anti-snag zippers, cinchable hood, zipper draft tube, puffed draft collar, and a two-way entry zipper.
Understanding sleeping bag ratings, click here.
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What's Included
Compression Sack and Storage Sack
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size + Specifications
Weight:
Short: 1021g
Short Wide: 1274g
Regular: 1205g
Regular Wide: 1515g
Long: 1398g
Long Wide: 1737g
Temperature Ratings:
EN Comfort: 0°C (32°F)
EN Limit: -6°C (20°F)
EN Extreme: -23°C (-9°F)
Fits User Height:
Short / Short Wide: up to 168cm
Regular / Regular Wide: up to 183cm
Long / Long Wide: up to 198cm
Bag Length:
Short / Short Wide: 188cm
Regular / Regular Wide: 203cm
Long / Long Wide: 216cm
Girth (Shoulder / Hip / Foot Box):
Short: 160cm / 150cm / 155cm
Short Wide: 191cm / 185cm / 155cm
Regular: 163cm / 152cm / 155cm
Regular Wide: 193cm / 188cm / 155cm
Long: 165cm / 155cm / 155cm
Long Wide: 196cm / 191cm / 155cm
Packed Dimensions:
Short: 24 x 17cm
Short Wide: 25 x 17cm
Regular: 32 x 19cm
Regular Wide: 34 x 19cm
Long: 33 x 19cm
Long Wide: 37 x 19cm
Fill:
650-fill duck down
PFAS-free hydrophobic treatment
RDS certified
Fill Weight:
Short: 565g
Short Wide: 768g
Regular: 649g
Regular Wide: 909g
Long: 733g
Long Wide: 1030g
Shell Fabric: 20D 100% recycled nylon ripstop
Lining Fabric: 20D 100% recycled nylon ripstop
Zipper Side: Left
Colour: Morning Blue -
what we think
Our gear expert Dan has spent time using the Boost while wild camping in Snowdonia, and it's proven to be a dependable option for three-season use in the UK. With chilly nights, damp conditions and exposed terrain, the Boost held up well, providing reliable warmth and comfort without adding too much weight to the pack.
The 650-fill hydrophobic down may not be aimed at the ultralight crowd, but it strikes a good balance between packability, insulation and price. The recycled nylon fabric and PFAS-free treatment are nice touches too, showing a clear move toward more responsible design.
With a roomy fit and solid construction, it’s a great choice for wild campers looking for comfort and durability over extreme weight savings. If you're planning nights out in the hills or a long weekend hike in mixed conditions, the Boost is well worth considering. -
reviews
"This bag has features that were obviously well thought out, designed and implemented. The simplicity of warm zip with the amount of functional utility it provides in adjust temp and fit of the bag is incredible. The arm holes are large enough that I have no trouble opening and using when full zipped in the bag, and the pocket, while modest, is all I need to keep my electronics from migrating out of reach overnight."
"Super comfy bag, so much space that it's basically a barrel bag that converts to a mummy. The material feels so nice against the skin, the down is evenly distributed and lofts well. The zippers perform flawlessly, I've tried to make them snag and they don't! The arm holes are a great idea and not something I knew I needed until now" -
Weight
1210 g
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Fill Power
650
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Season Rating
3-Season
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Comfort Limit
-6°C
"The Valley and Peak promise is built on three pillars: thoughtfully curated gear, exceptional customer service, and a genuine love for the outdoors. As an independent, family-run business, we carefully select products from a wide variety of cottage gear brands and trusted names, ensuring that each item is rigorously tested and loved by our team. Our customer service is a cornerstone of our brand, offering personalised support to help you choose and care for your gear with confidence"
Jim De'Ath, Managing Director