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Bear Grylls Emergency Bivy vs Fox 40 Micro Whistle

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

Fox 40 Micro Whistle is the lighter option — 103 g lighter than the Bear Grylls Emergency Bivy (91% less weight). If grams matter to you, that is the one to beat.
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Spec Bear Grylls Emergency Bivy Fox 40 Micro Whistle
Weight 113 g · 0.113 kg · 0.25 lb 10 g · 0.010 kg · 0.02 lb
Brand Bear Grylls Fox 40
Category Safety Safety
Bear Grylls Emergency Bivy
113 g

Tear and puncture-resistant mylar bivy. Only 4 oz for emergency backup shelter.

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Fox 40 Micro Whistle
10 g

Pealess safety whistle audible up to 1km.

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Bear Grylls Emergency Bivy vs Fox 40 Micro Whistle: which should you buy?

If saving weight is your priority, the Fox 40 Micro Whistle wins — at 10 g it is 103 g (91%) lighter than the Bear Grylls Emergency Bivy (113 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 safety page, or browse the full gear weight database.

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