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

The Spark 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 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.

Their 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 Spark an impressive hard-alpine or adventure racing bag, where every gram is counted and down has never been a viable option.

Technologies

Differential Cut Shell - Down insulates best when it is uncompressed and fully lofted. To help the down loft correctly we use a differential cut shell and lining. The top shell of all Sea to Summit sleeping bags is cut larger than the lining. This creates space in between for the down to loft fully. In the bottom of the bag we use a reverse differential cut. By increasing the size of the lining relative to the shell, down lofts up to fill the voids around your body, torso, legs and the small of your back. Trapping heat close to the skin is essential for efficient warm sleeping.

Down Loft, Fill Power - Down is the soft plumage of birds that lives under the feathers. A single piece of down is called a plume. The majority of down used in clothing and bedding comes from geese and ducks. Down is one of the best warmth to weight insulators available. It is not only warmer for weight, but compresses much smaller and is much more durable than most synthetic fill equivalents.
Loft is the volume for a given weight of down. High loft down is warmer for a given weight than low loft down. The most common measure of loft is fill power, a term which is often used interchangeably with loft. Fill power is the volume, in cubic inches, that an ounce of down will fill. Thus, one ounce of 650 loft down will fill 650in3.
Composition refers to the percentage of down versus feathers in a batch of down. In Australian and US regulation, 90/10 means that 90% of the batch is down plumes, the other 10% is small feathers. The higher this ratio, the lighter, softer and more compressible a sleeping bag will be. It also means there are fewer feather quills or spines to poke through the stitching or fabric of a bag.

EN13537 Temperature Rating System - EN13537 is a European standard for sleeping bag temperature ratings.
Everyone sleeps differently; some people are very warm sleepers while others feel the cold easily. There are many factors that affect your warmth and comfort in a sleeping bag. An important factor is that you use a good insulating mat to prevent your body heat from being drawn into the cold ground. Other factors include your tent or shelter, gender and metabolism, clothing, sleeping bag liner, use of the hood and your daily calorie intake.
Although the EN13537 standard does not identify a single precise temperature a tested sleeping bag is suitable for, it does provide an industry standardised temperature range that a typical user can refer to as a guide for the conditions their bag will be most comfortable in.
The EN13537 standard provides three temperature levels to guide a consumer in their choice:
Comfort: The temperature at which a standard woman can expect to sleep comfortably in a relaxed position. If you consider yourself a cold sleeper use this rating to decide the coldest temperature the sleeping bag is suitable for.
Lower Limit: The temperature at which a standard man can sleep for eight hours in a curled position without waking. If you consider yourself a warm sleeper you can use this rating to decide the coldest temperature the sleeping bag is suitable for.
Extreme: This is a survival only rating for a standard woman. Between the lower limit and the extreme rating a strong sensation of cold has to be expected and there is a risk of health damage due to hypothermia. This is an extreme survival rating only, they do not recommend you rely on this rating for general use.
The EN13537 temperature tests use a thermal manikin with heaters and temperature sensors to measure the insulation value of a sleeping bag. This manikin is wearing one layer of long underwear and is placed inside the sleeping bag on an insulating mat. The test is conducted in a temperature controlled chamber and a range of comfort temperatures are derived from measuring the energy required to maintain homeostasis in the manikin
to a set temperature.

Responsible Down Standards - Sea to Summit Sleeping bags use down that has been sourced and certified by the Responsible Down Standard (RDS). The RDS is helping to shift the entire down and feather industry towards more humane animal rearing and handling practices. Overseen by the industry leading Textile Exchange, the RDS requires independent, third party assessments of all aspects of animal rearing and handling throughout the entire supply chain. By only using down that meets the audited requirements of the RDS we can have confidence that each phase of the collection process has been completed with the welfare and ethical treatment of waterfowl in mind. To find out more information about how the RDS is improving animal welfare during down collection, please visit responsibledown.org

UL 10 Denier Nylon - UL 10 Denier Nylon is their lightest weight sleeping bag fabric used in their Spark sleeping bags to keep them ultra lightweight and with maximum compressibility

UL 15 Denier Nylon - UL 15 Denier Nylon is a lightweight sleeping bag fabric that we use in our Spark and Traveller sleeping bags to keep them ultra light and with with maximum compressibility

Ultra-Dry Down - Ultra-Dry Down is a permanent* Nano-level water repellent polymer treatment applied to our high loft, high quality down. The Nano-thin treatment vastly improves our downs reaction to water without effecting its weight or loft performance. ULTRA-DRY Down retains over 60% more loft and absorbs 30% less moisture when compared with untreated down. Sea to Summit sleeping bags dry out 60% faster than bags with untreated down.
The Nano-level treatment also inhibits bacterial and microbial growth, which makes Sea to Summit sleeping bags more hygienic and improves their lifespan.

*No loss of treatment effect has been seen in over 14 wash cycles.

Features

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
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 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
Includes lightweight Ultra-Sil Nano compression bag for compact storage

Specifications

Size Variation Regular Long
Recommended User Height up to 183cm up to 198cm
Packed Dimensions 15 x 35cm 15 x 35cm
Volume Compressed 4.6L 5.4L
Compression Sack Volume (Compressed) 6 to 2L 6 to 2L
Weight 665g 745g
Fill Weight 430g 485g
Internal Chest Circumference 155cm 162cm
Internal Hip Circumference 135cm 142cm
Internal Foot Circumference 94cm 100cm

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