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Sea to Summit
TK III 12° F Sleeping Bag

Out of Stock  Product Number: 25338

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The Sea to Summit TK III 12 degree sleeping bag is the warmest in the Trek Series, an excellent companion for winter camping or a long night in a cold train station. This down sleeping bag is EN-rated to a lower-limit temperature of 12 degrees F and a comfort temperature of 23 degrees F.

The Trek Series down sleeping bags are designed with a tapered rectangular shape, which is a happy medium between the comfort of a generous cut and the warmth of a closer fit. Sea to Summit uses premium 650 loft down insulation, with a 2D PermaShell™ DWR (Durable Water Repellent) shell fabric to protect that down from moisture. Innovations like the 3D Sidewall and Reverse Differential Cut keep the insulation in place for maximum thermal efficiency. Temperature ratings are the result of honest, third-party EN testing performed on each sleeping bag.

The TK III features a full-length side and foot zip so it can be opened into a full duvet, for use indoors or in warmer weather. Side block baffles maintain a 60:40 fill ratio, with more down atop the bag where you need it most. The soft-touch lining fabric is highly breathable for comfort. A zipper draft tube minimizes heat loss, with anti-snag material to ensure smooth zipper operation. An oversized security pocket inside the bag is easy to access, and ideal for stashing passports and other valuables while traveling.

The Trek series is Sea to Summit's choice for adventure travel and touring, whether you're sleeping in hostels throughout Europe, backpacking in South America or traveling through the Stirling Ranges in Western Australia. These down sleeping bags are so revolutionary we can’t fit all of the information here, so check out this series of articles on our blog!

* This product does not qualify for shipping to all countries.


  • Tapered rectangular
  • 2D PermaShell™ DWR shell fabric
  • Differential cut shell with 3D side walls
  • 60/40 fill ratio
  • Side block baffle
  • Zip draft tube with anti-snag
  • Cushioned internal hood drawcord with dual adjustment
  • 2 way YKK #5 zips with separate foot zip
  • Large sized internal zip pocket
  • Includes lightweight Ultra-Sil® compression bag, mesh storage cell and laundry bag
  • Down: 650 Loft 85/15 Premium Down
  • Fill Weight: Short: 24.69 oz / 700 grams Regular: 24.69 oz / 700 grams Long: 26.46 oz / 750 grams
  • Bag Weight: Short: 2.65 pounds / 1200 grams Regular: 2.69 pounds / 1220 grams Long: 2.87 pounds / 1310 grams
  • Recommended Max Height: Short:<5' 5" Regular: <6' Long : <6'7"
  • Sleeping bag dimensions Internal circumference (Chest, Hip Foot): Short: 59.05", 58.27," 39.37" Regular: 59.84", 59.05", 39.76" Long : 61.42", 59.84", 40.16"
  • Temp Rating: Comfort: 23 DegreeF / -5 DegreeC Lower Limit: 12 DegreeF / -11 DegreeC Extreme: -22 DegreeF / -30 DegreeC
  • Zipper Option: Short: Right only Regular: Left or Right Long: Left only
  • Season Rating: Spring/Autumn/Winter-lite
  • Suggested Use: Backpacking, travel, hiking, camping
  • Compression Bag: Medium - 15L to 5L

Gender: Unisex
Zipper Type: Left Zip
Season: F13
Vendor ProductId: 043LL
Review ProductId: 25338

Interested in some of the more technical elements included in the Sea to Summit Trek Series of down sleeping bags? Check out our series of blog articles about these sleeping bag features:

3D Sidewall & Reverse Differential Cut
EN temperature ratings

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