Durston Kakwa 55 (2025) vs Osprey Sirrus 36

Weight and specs compared for 2026 — and which one to choose.

Durston Kakwa 55 (2025) is the lighter option — 370 g lighter than the Osprey Sirrus 36 (30% less weight). If grams matter to you, that is the one to beat.

Spec	Durston Kakwa 55 (2025)	Osprey Sirrus 36
Weight	850 g · 0.850 kg · 1.87 lb	1,220 g · 1.220 kg · 2.69 lb
Brand	Durston	Osprey
Category	Backpack	Backpack

Durston Kakwa 55 (2025)

850 g

55L ultralight thru-hiking pack in Ultra 200X fabric with tubular aluminum frame, carries up to 20kg comfortably.

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Osprey Sirrus 36

1,220 g

Women's ventilated 36L pack with AirSpeed back panel.

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Durston Kakwa 55 (2025) vs Osprey Sirrus 36: which should you buy?

If saving weight is your priority, the Durston Kakwa 55 (2025) wins — at 850 g it is 370 g (30%) lighter than the Osprey Sirrus 36 (1,220 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.

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