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MSR Guardian Purifier Pump vs SteriPen Adventurer Opti

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

SteriPen Adventurer Opti is the lighter option — 400 g lighter than the MSR Guardian Purifier Pump (82% less weight). If grams matter to you, that is the one to beat.
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Spec MSR Guardian Purifier Pump SteriPen Adventurer Opti
Weight 490 g · 0.490 kg · 1.08 lb 90 g · 0.090 kg · 0.20 lb
Brand MSR SteriPen
Category Hygiene Hygiene
MSR Guardian Purifier Pump
490 g

Military-grade water purifier removes viruses, bacteria and protozoa.

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SteriPen Adventurer Opti
90 g

UV water purifier. Purifies 1L in 90 seconds.

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MSR Guardian Purifier Pump vs SteriPen Adventurer Opti: which should you buy?

If saving weight is your priority, the SteriPen Adventurer Opti wins — at 90 g it is 400 g (82%) lighter than the MSR Guardian Purifier Pump (490 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 hygiene page, or browse the full gear weight database.

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