Durston Gear Kakwa 40 vs Outdoor Vitals CS40 Ultra
Weight and specs compared for 2026 — and which one to choose.
Ultralight 40L internal-frame thru-hiking pack in Ultra 200X fabric, with a hollow aluminum U-frame and 15L of external storage.
Ultralight 40L backpack built for ultralight hiking and thru-hiking. Features innovative weight-saving construction that carries 20x its weight.
Building a pack? Add either one to your HikeLoad list, or drop its weight into the base weight calculator, and see what it does to your total weight.
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Durston Gear Kakwa 40 vs Outdoor Vitals CS40 Ultra: which should you buy?
If saving weight is your priority, the Outdoor Vitals CS40 Ultra wins — at 765 g it is 30 g (4%) lighter than the Durston Gear Kakwa 40 (795 g). That said, the heavier option may justify the extra grams with more capacity, durability or comfort, so weigh the trade-off against how you'll use it.
See where both rank against everything else in this category on the lightest backpack page, or browse the full gear weight database.