Osprey Exos 58 Backpack vs REI Co-op Flash 45

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

REI Co-op Flash 45 is the lighter option — 86 g lighter than the Osprey Exos 58 Backpack (7% less weight). If grams matter to you, that is the one to beat.

Spec	Osprey Exos 58 Backpack	REI Co-op Flash 45
Weight	1,276 g · 1.276 kg · 2.81 lb	1,190 g · 1.190 kg · 2.62 lb
Brand	Osprey	REI Co-op
Category	Backpack	Backpack

Osprey Exos 58 Backpack

1,276 g

Lightweight ventilated backpack with AirSpeed suspended mesh back panel. Floating top lid, large front pocket. Great all-day comfort for summer hikes.

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REI Co-op Flash 45

1,190 g

Lightweight 45L versatile backpacking pack.

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Osprey Exos 58 Backpack vs REI Co-op Flash 45: which should you buy?

If saving weight is your priority, the REI Co-op Flash 45 wins — at 1,190 g it is 86 g (7%) lighter than the Osprey Exos 58 Backpack (1,276 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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