Sea to Summit Trek TkII 18 Sleeping Bag

$349.00to $369.00
Color: Denim/Navy
please select a Size
Choose a shipping method

With a tapered rectangular shape that offers more room than a mummy bag, the Sea to Summit Trek TkII sleeping bag keeps you warm via water-resistant, RDS-certified 650-fill-power down.

  • Features

    • Water-repellent, 650-fill-power Ultra-Dry Down™ retains 60% more loft and absorbs 30% less moisture than untreated down; down is also PFC-free and RDS-certified
    • Responsible Down Standard (RDS) ensures the down does not come from animals that have been subject to any unnecessary harm, such as force-feeding or live-plucking
    • Tapered rectangular shape offers more space than a traditional mummy bag while maintaining thermal efficiency
    • Nylon shell fabric is treated with a durable water repellent (DWR) finish that sheds moisture and helps block wind
    • Vertical chest baffles prevent down migration and 3D sidewall baffle maximizes loft right to the edge of the bag to prevent cold spots
    • 2-way #5 YKK® side and foot zippers let you ventilate as needed; oversized zip draft tube keeps out the drafts, while antisnag materials make for smooth zipping
    • 3D hood draws in tight to keep you cozy; neck collar draft tube seals in warmth
    • 20-denier lining fabric is lightweight and soft on your skin
    • Internal security pocket keeps nighttime essentials close at hand
    • Comes with an Ultra-Sil™ compression sack and a nylon storage sack
    • This bag is designed to zip together with another to create a double bag


    Many sleeping bags are rated for temperature by an independent testing protocol. REI and the broader industry now use the International Organization for Standardization (ISO) 23537 protocol, which improves on the older European Norm (EN) 13537 standard; you may still see older items in our assortment that were only EN tested. With either protocol, each bag gets a Comfort (or T-Comfort) rating and Lower Limit (or T-Limit) rating. The Comfort rating is the lowest temperature at which the bag will keep the average "cold sleeper" comfortable, and the Lower Limit rating is the lowest temperature at which the bag will keep the average "warm sleeper" comfortable. Ratings are based on a person wearing one long underwear layer and a pair of socks, sleeping on an insulated surface with a minimum R-value of 5.38. Many brands use the Comfort rating for women's bags and the Lower Limit rating for men's and unisex bags. Everyone's body and sleep comfort differ, and conditions of use (posture, clothing, sleeping pad R-value, wind, humidity, etc.) affect total insulation, so EN and ISO ratings are intended as a guideline to help you compare products, rather than a guarantee of warmth.
    View all Sea to Summit Men's Sleeping Bags
  • Technical Specs

    Best Use


    Tested Lower Limit

    18 degrees (F) - EN

    Tested Comfort

    30 degrees (F) - EN

    Temperature Rating (F)

    18 degrees (F)

    Temperature Rating (C)

    -7.8 degrees (C)


    Regular: 2 lbs. 2 oz.

    Long: 2 lbs. 6 oz.


    30-denier nylon

    Zipper Location


    Insulation Type


    Water-Resistant Down



    650-fill-power Ultra-Dry down

    Fill Weight

    Regular: 1 lb. 2 oz.

    Long: 1 lb. 4 oz.


    20-denier nylon

    Sleeping Bag Shape


    Fits Up To (in.)

    Regular: 72 inches

    Long: 76 inches

    Shoulder Girth (in.)

    Regular: 60 inches

    Long: 64 inches

    Hip Girth (in.)

    Regular: 57 inches

    Long: 62 inches

    Stuff Sack Size


    Stuff Sack Volume

    Regular: 10 liters

    Long: 14 liters

    Compressed Volume

    Regular: 6.1 liters

    Long: 7.3 liters




    Down certified to the Responsible Down Standard (RDS)

  • Reviews
    30 reviews with an average rating of 4.4 out of 5 stars

    Loading Reviews...
  • Questions & Answers

    Loading Questions...