Sea to Summit Womens Flame IV Down Sleeping Bag

-17°C Comfort Limit (EN13537:2012), 650g of 850+ Fill Power ULTRA-DRY Down (US Method)
Weighs 892g (Regular bag)
Code: AW19603
  • Now £489.99
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The Sea to Summit Women's Flame FmIV is minimalist in the true sense of the word, it only includes a few key features but delivers exceptional warmth given its very low weight.

Sea to Summit says:

Ultra-light and technical, our Flame Series bags are designed to keep you as warm as possible while minimising packed weight and size.

The Flame Series spans everything from an ultralight liner to an expedition weight mid-winter bag. While the end usage is very different, they reflect a design ethos of matching weather conditions to the lightest bag possible.

The secret to the impressive performance is a combination of premium materials and careful design. The RDS 850+ Loft premium goose down, light-gauge #3 YKK zip and high performance 10D Nylon shell and 7D lining fabrics, set the stage for a superior performance. These materials are combined with a contoured mummy design for efficient insulation, and that mummy design is then tweaked for each model to best fit the use scenario.

The women's specific fit is wider at the hip and narrower at the shoulder and we've added extra down overall for increased warmth.

Our Ultra-Dry Down water-repellent treatment protects the down from external moisture and condensation from the inside of the bag, virtually eliminating the negative effects moisture has on down. All Sea to Summit Down Sleeping Bags use Responsible Down Standard (RDS) certified down. The Ultra-Dry Down protection also makes the Flame an impressive hard-alpine or adventure racing bag, where every gram is counted and down has never been a viable option.

Sea to Summit's Womens Flame FmIV Down Sleeping Bag is a true minimalist bag that uses the lightest materials and highest quality, responsibly sourced  down to deliver an exceptionally high warmth to weight ratio, when compared to other similarly rated bags.

The Flame IV bag features vertical baffles on the chest area to minimise movement of down, optimising insulation where you need it most. The bag uses box wall construction throughout which reduces the cold spots you get with sewn construction. The full zip with 2 sliders allows good venting options if conditions are too warm. There is a small insulating zip baffle and further draft collars around the head to limit heat loss.

The contoured mummy shape is roomy and the super thin and light outer fabrics means more care will be needed than with more heavy duty bags. The bag compresses down to a very small size.

- Reviewed by Ultralight Outdoor Gear

Read reviews here:
Help and advice:Choosing a sleeping bag advice
 EN 13537 rating for sleeping bags explained
 Sleeping bag shape and sizes advice
 Sleeping Bag features Page 1
 All about down filling in sleeping bags
  • Women's specific contoured mummy shape for efficient insulation
  • Ultralight 7D and 10D fabrics for minimal weight and packed size
  • RDS 850+ Loft Premium Goose ULTRA-DRY Down for maximum insulation value
  • Contoured mummy shape for comfort and efficient insulation
  • Vertical chest baffles prevent down migration and cold spots
  • This bag is not designed to pair with another
  • Uses a full box baffle construction to accommodate extra down and reduce cold spots
  • Expedition mummy bag sizing provides extra space for layered clothing or extra wriggle room
  • Vertical baffles on chest optimises positions of down to prevent it from moving during use
  • Full side zip with two sliders provides easy access and extra ventilation options
  • Zipper draft tube, hood and front neck draft collar to prevent warmth being lost when it's needed

Temperature Rating

  • EN13537:2012 Comfort: -10°C / 15°F
  • EN13537:2012 Comfort Limit: -17°C / 1°F
  • EN13537:2012 Extreme: -38°C / -36°F

Regular Specs

  • Weight: 892g (excludes storage bags)
  • Fill weight: 650g
  • Fits up to: 5 ft 7 in / 170 cm
  • Internal Width Shoulder: 150cm / 59 in
  • Internal Width Waist: 142cm / 56 in
  • Internal Width Feet: 90cm / 35.5 in


  • Insulation: RDS 850+ Loft Premium Goose ULTRA-DRY Down
  • Shell: Ultralight 10D Nylon Shell
  • Zipper: Right-side #3 YKK zipper
  • Comes with: Ultra-Sil™ compression bag and storage cell
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