Description
SIZE IS LONG
Traditional comfort and value, with an anything but traditional design approach, the Trek Series sleeping bags are what STS grab for globe-trotting adventures on a budget. Vertical baffles over the chest section ensure the down insulation cannot migrate or shift to the outside of the bag during sleep, creating cold spots. A side block baffle construction maintains the 60/40 fill ratio, keeping more down on the top of the bag for maximum insulation.
Suggested use: Trekking/Hiking, Camping, Travel
Season ratings: Spring/Autumn/Winter
Lightweight fabrics reduce weight and packed bulk while the two-way #5 YKK full length side zip and separate foot zip, allows the bag to open out completely and double as a quilt. The foot zip is perfect for extra ventilation or to provide freedom of movement for your feet. 
The 3D side-wall baffle ensures that down can loft to the very edge of the bag, maximising insulation, while the panelled hood draws in tight when needed or lies flat for use in warmer weather. The oversized zipper draft tube uses anti-snag materials to prevent the zipper catching and the soft-touch 20D lining fabric is highly breathable yet also down proof.
Completing the thoughtful design features of this classic down bag, STS have included a large internal security pocket, perfect for keeping valuables close or batteries warm.
With use of the zip coupling feature
 
Features:
Tapered rectangular for more space and comfort than a traditional mummy bag
RDS 650+ Loft ULTRA-DRY Down offers excellent insulation and compressibility
Lightweight fabrics for reduced weight and bulk
Vertical chest baffles prevent down migration and cold spots
Two-way #5 YKK side and separate foot zip allows bag to double as a quilt and provides extra ventilation options
Oversized zip draft tube with anti-snag materials
Large internal security pocket
3D side-wall baffle maximises down insulation right to the edge of the bag
3D hood draws in tight when needed
Trek Tk3 has additional neck collar draft tube to seal and trap in all your warmth
Soft touch 20D lining fabric is lightweight and highly breathable, durable 30D Nylon shell
Includes Ultra-Sil Compression Bag for compact storage
Zip Coupling - This bag is designed to pair with another
Shell: 100% Nylon, Lining: 100% Nylon, Primary Filling Material: DUCK DOWN (Min. 85% Down), Stuffsack: 100% Nylon excluding Trims
Product Details
 
Series:
Sea to Summit : Sleeping Bags : Trek
Manufacturer Colour:
Blue
Material:
20D Nylon Shell, 20D Nylon Shell, Ultra Dry Down 650+ Loft 85/15 Premium Duck Down
Weight:
 Long - 1.13 kg

 
Long: for people up to 198 cm / 6'6"
Fill weight:  Long - 780g
Compression Sack Size : Med (14 - 4.5L)
Construction
Differential Cut Shell & Lining
Down insulates best when it is uncompressed and fully lofted. To help the down loft correctly, Sea to Summit uses 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 addition they use 3D side walls which gives the distinctive vertical sides to their sleeping bags, this further aids vertical loft along both sides of the bag. In the bottom of the bag, they 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.

Side Block Baffle & Fill Ratio
The loft is optimised using a side block baffle construction which allows the bags to be filled with a different ratio of down in the top and bottom. Sea to Summit sleeping bags have more down in the top of the bag where it is most effective as the down isn’t compressed by your body weight. The exact ratio of down fill must be matched to the shape of a sleeping bag.